diff --git a/src/components/NotePostForm.tsx b/src/components/NotePostForm.tsx
index 6f8fab4..5a67306 100644
--- a/src/components/NotePostForm.tsx
+++ b/src/components/NotePostForm.tsx
@@ -13,6 +13,7 @@ import UserNameDisplay from '@/components/UserDisplayName';
 import useConfig from '@/core/useConfig';
 import useEmojiComplete from '@/hooks/useEmojiComplete';
 import usePersistStatus from '@/hooks/usePersistStatus';
+import { useTranslation } from '@/i18n/useTranslation';
 import { textNote } from '@/nostr/event';
 import parseTextNote, { ParsedTextNote } from '@/nostr/parseTextNote';
 import useCommands, { PublishTextNoteParams } from '@/nostr/useCommands';
@@ -28,16 +29,6 @@ type NotePostFormProps = {
   textAreaRef?: (textAreaRef: HTMLTextAreaElement) => void;
 };
 
-const placeholder = (mode: NotePostFormProps['mode']) => {
-  switch (mode) {
-    case 'reply':
-      return '返信を投稿';
-    case 'normal':
-    default:
-      return 'いまどうしてる？';
-  }
-};
-
 const extract = (parsed: ParsedTextNote) => {
   const hashtags: string[] = [];
   const pubkeyReferences: string[] = [];
@@ -86,6 +77,7 @@ const format = (parsed: ParsedTextNote) => {
 };
 
 const NotePostForm: Component<NotePostFormProps> = (props) => {
+  const i18n = useTranslation();
   let textAreaRef: HTMLTextAreaElement | undefined;
   let fileInputRef: HTMLInputElement | undefined;
 
@@ -108,6 +100,16 @@ const NotePostForm: Component<NotePostFormProps> = (props) => {
     props.onClose();
   };
 
+  const placeholder = (mode: NotePostFormProps['mode']) => {
+    switch (mode) {
+      case 'reply':
+        return i18n()('posting.placeholderReply');
+      case 'normal':
+      default:
+        return i18n()('posting.placeholder');
+    }
+  };
+
   const { config, getEmoji } = useConfig();
   const { persistStatus, didAgreeToToS, agreeToToS } = usePersistStatus();
   const getPubkey = usePubkey();
@@ -152,7 +154,7 @@ const NotePostForm: Component<NotePostFormProps> = (props) => {
 
       if (failed.length > 0) {
         const filenames = failed.map((f) => f.name).join(', ');
-        window.alert(`ファイルのアップロードに失敗しました: ${filenames}`);
+        window.alert(i18n()('posting.failedToUploadFile', { filenames }));
       }
     },
   });
@@ -194,7 +196,7 @@ const NotePostForm: Component<NotePostFormProps> = (props) => {
     if (publishTextNoteMutation.isLoading) return;
 
     if (/nsec1[0-9a-zA-Z]+/.test(text())) {
-      window.alert('投稿に秘密鍵(nsec)を含めることはできません。');
+      window.alert(i18n()('posting.forbiddenToIncludeNsec'));
       return;
     }
 
@@ -337,6 +339,7 @@ const NotePostForm: Component<NotePostFormProps> = (props) => {
     <div class="p-1">
       <Show when={props.replyTo != null}>
         <div>
+          {i18n()('posting.replyToPre')}
           <For each={notifyPubkeys()}>
             {(pubkey, index) => (
               <>
@@ -345,7 +348,7 @@ const NotePostForm: Component<NotePostFormProps> = (props) => {
               </>
             )}
           </For>
-          に返信
+          {i18n()('posting.replyToPost')}
         </div>
       </Show>
       <form class="flex flex-col gap-1" onSubmit={handleSubmit}>
@@ -353,7 +356,7 @@ const NotePostForm: Component<NotePostFormProps> = (props) => {
           <input
             type="text"
             class="rounded"
-            placeholder="警告の理由"
+            placeholder={i18n()('posting.contentWarningReason')}
             maxLength={32}
             onInput={(ev) => setContentWarningReason(ev.currentTarget.value)}
             value={contentWarningReason()}
@@ -400,8 +403,8 @@ const NotePostForm: Component<NotePostFormProps> = (props) => {
               'w-7': mode() === 'reply',
             }}
             type="button"
-            aria-label="コンテンツ警告を設定"
-            title="コンテンツ警告を設定"
+            aria-label={i18n()('posting.contentWarning')}
+            title={i18n()('posting.contentWarning')}
             onClick={() => setContentWarning((e) => !e)}
           >
             <span>CW</span>
@@ -417,8 +420,8 @@ const NotePostForm: Component<NotePostFormProps> = (props) => {
               'w-7': mode() === 'reply',
             }}
             type="button"
-            title="画像を投稿"
-            aria-label="画像を投稿"
+            title={i18n()('posting.uploadImage')}
+            aria-label={i18n()('posting.uploadImage')}
             disabled={fileUploadDisabled()}
             onClick={() => fileInputRef?.click()}
           >
@@ -435,8 +438,8 @@ const NotePostForm: Component<NotePostFormProps> = (props) => {
               'w-7': mode() === 'reply',
             }}
             type="submit"
-            aria-label="投稿"
-            title="投稿"
+            aria-label={i18n()('posting.submit')}
+            title={i18n()('posting.submit')}
             disabled={submitDisabled()}
           >
             <PaperAirplane />
diff --git a/src/components/event/EventDisplayById.tsx b/src/components/event/EventDisplayById.tsx
index 5ef93a2..ca7e071 100644
--- a/src/components/event/EventDisplayById.tsx
+++ b/src/components/event/EventDisplayById.tsx
@@ -5,6 +5,7 @@ import EventDisplay from '@/components/event/EventDisplay';
 import { type EventDisplayProps } from '@/components/event/EventDisplay';
 import EventLink from '@/components/EventLink';
 import useConfig from '@/core/useConfig';
+import { useTranslation } from '@/i18n/useTranslation';
 import useEvent from '@/nostr/useEvent';
 import ensureNonNull from '@/utils/ensureNonNull';
 
@@ -13,6 +14,7 @@ type EventDisplayByIdProps = Omit<EventDisplayProps, 'event'> & {
 };
 
 const EventDisplayById: Component<EventDisplayByIdProps> = (props) => {
+  const i18n = useTranslation();
   const [localProps, restProps] = splitProps(props, ['eventId']);
   const { shouldMuteEvent } = useConfig();
 
@@ -31,7 +33,7 @@ const EventDisplayById: Component<EventDisplayByIdProps> = (props) => {
     <Switch
       fallback={
         <span>
-          投稿が見つかりません
+          {i18n()('post.failedToFetchEvent')}
           {props.eventId}
         </span>
       }
@@ -43,8 +45,7 @@ const EventDisplayById: Component<EventDisplayByIdProps> = (props) => {
       <Match when={eventQuery.isLoading && localProps.eventId} keyed>
         {(id) => (
           <div class="truncate">
-            {'読み込み中 '}
-            <EventLink eventId={id} />
+            {i18n()('general.loading')} <EventLink eventId={id} />
           </div>
         )}
       </Match>
diff --git a/src/components/event/Reaction.tsx b/src/components/event/Reaction.tsx
index 3704336..af21355 100644
--- a/src/components/event/Reaction.tsx
+++ b/src/components/event/Reaction.tsx
@@ -68,7 +68,11 @@ const ReactionDisplay: Component<ReactionDisplayProps> = (props) => {
       <div class="notification-event py-1">
         <Show
           when={reactedEvent()}
-          fallback={<div class="truncate">読み込み中 {eventId()}</div>}
+          fallback={
+            <div class="truncate">
+              {i18n()('general.loading')} {eventId()}
+            </div>
+          }
           keyed
         >
           {(ev) => <TextNoteDisplay event={ev} />}
diff --git a/src/components/modal/ProfileDisplay.tsx b/src/components/modal/ProfileDisplay.tsx
index d031b36..a5cbd75 100644
--- a/src/components/modal/ProfileDisplay.tsx
+++ b/src/components/modal/ProfileDisplay.tsx
@@ -131,21 +131,14 @@ const ProfileDisplay: Component<ProfileDisplayProps> = (props) => {
 
       const latest = await fetchLatestFollowings({ pubkey: p });
 
-      const msg = stripMargin`
-        フォローリストが空のようです。初めてのフォローであれば問題ありません。
-        そうでなければ、リレーとの接続がうまくいっていない可能性があります。ページを再読み込みしてリレーと再接続してください。
-        また、他のクライアントと同じリレーを設定できているどうかご確認ください。
-
-        続行しますか？
-      `;
-
-      if ((latest.data() == null || latest.followingPubkeys().length === 0) && !window.confirm(msg))
+      if (
+        (latest.data() == null || latest.followingPubkeys().length === 0) &&
+        !window.confirm(i18n()('profile.confirmUpdateEvenIfEmpty'))
+      )
         return;
 
       if ((latest?.data()?.created_at ?? 0) < (myFollowingQuery.data?.created_at ?? 0)) {
-        window.alert(
-          '最新のフォローリストを取得できませんでした。リレーの接続状況が悪い可能性があります。',
-        );
+        window.alert(i18n()('profile.failedToFetchLatestFollowList'));
         return;
       }
 
@@ -171,7 +164,7 @@ const ProfileDisplay: Component<ProfileDisplayProps> = (props) => {
       });
     } catch (err) {
       console.error('failed to update contact list', err);
-      window.alert('フォローリストの更新に失敗しました。');
+      window.alert(i18n()('profile.failedToUpdateFollowList'));
     } finally {
       setUpdatingContacts(false);
     }
@@ -184,7 +177,7 @@ const ProfileDisplay: Component<ProfileDisplayProps> = (props) => {
   };
 
   const unfollow = () => {
-    if (!window.confirm('本当にフォロー解除しますか？')) return;
+    if (!window.confirm(i18n()('profile.confirmUnfollow'))) return;
 
     updateContacts('unfollow', props.pubkey).catch((err) => {
       console.log('failed to unfollow', err);
@@ -384,11 +377,11 @@ const ProfileDisplay: Component<ProfileDisplayProps> = (props) => {
       </Show>
       <div class="flex border-t px-4 py-2">
         <button class="flex flex-1 flex-col items-start" onClick={() => setModal('Following')}>
-          <div class="text-sm">フォロー</div>
+          <div class="text-sm">{i18n()('profile.following')}</div>
           <div class="text-xl">
             <Show
               when={userFollowingQuery.isFetched}
-              fallback={<span class="text-sm">読み込み中</span>}
+              fallback={<span class="text-sm">{i18n()('general.loading')}</span>}
             >
               {userFollowingPubkeys().length}
             </Show>
@@ -396,7 +389,7 @@ const ProfileDisplay: Component<ProfileDisplayProps> = (props) => {
         </button>
         <Show when={!config().hideCount}>
           <div class="flex flex-1 flex-col items-start">
-            <div class="text-sm">フォロワー</div>
+            <div class="text-sm">{i18n()('profile.followers')}</div>
             <div class="text-xl">
               <Show
                 when={showFollowers()}
@@ -405,7 +398,7 @@ const ProfileDisplay: Component<ProfileDisplayProps> = (props) => {
                     class="text-sm hover:text-stone-800 hover:underline"
                     onClick={() => setShowFollowers(true)}
                   >
-                    読み込む
+                    {i18n()('profile.loadFollowers')}
                   </button>
                 }
                 keyed
diff --git a/src/components/modal/ProfileEdit.tsx b/src/components/modal/ProfileEdit.tsx
index fed58e1..c911941 100644
--- a/src/components/modal/ProfileEdit.tsx
+++ b/src/components/modal/ProfileEdit.tsx
@@ -7,6 +7,7 @@ import omitBy from 'lodash/omitBy';
 
 import BasicModal from '@/components/modal/BasicModal';
 import useConfig from '@/core/useConfig';
+import { useTranslation } from '@/i18n/useTranslation';
 import { Profile } from '@/nostr/event/Profile';
 import useCommands from '@/nostr/useCommands';
 import useProfile from '@/nostr/useProfile';
@@ -29,6 +30,7 @@ const isLNURL = (s: string) => LNURLRegex.test(s);
 const isInternetIdentifier = (s: string) => InternetIdentifierRegex.test(s);
 
 const ProfileEdit: Component<ProfileEditProps> = (props) => {
+  const i18n = useTranslation();
   const pubkey = usePubkey();
   const { config } = useConfig();
 
@@ -56,11 +58,11 @@ const ProfileEdit: Component<ProfileEditProps> = (props) => {
       const succeeded = results.filter((res) => res.status === 'fulfilled').length;
       const failed = results.length - succeeded;
       if (succeeded === results.length) {
-        window.alert('更新しました');
+        window.alert(i18n()('profile.edit.updateSucceeded'));
       } else if (succeeded > 0) {
-        window.alert(`${failed}個のリレーで更新に失敗しました`);
+        window.alert(i18n()('profile.edit.failedToUpdatePartially', { count: failed }));
       } else {
-        window.alert('すべてのリレーで更新に失敗しました');
+        window.alert(i18n()('profile.edit.failedToUpdate'));
       }
       invalidateProfile()
         .then(() => query.refetch())
@@ -159,13 +161,13 @@ const ProfileEdit: Component<ProfileEditProps> = (props) => {
         </div>
       </div>
       <Show when={loading()}>
-        <div class="px-4 pt-4">読み込み中...</div>
+        <div class="px-4 pt-4">{i18n()('general.loading')}</div>
       </Show>
       <div>
         <form class="flex flex-col gap-4 p-4" onSubmit={handleSubmit}>
           <div class="flex flex-col items-start gap-1">
             <label class="font-bold" for="picture">
-              アイコン
+              {i18n()('profile.edit.icon')}
             </label>
             <input
               class="w-full rounded-md focus:border-rose-100 focus:ring-rose-300"
@@ -181,7 +183,7 @@ const ProfileEdit: Component<ProfileEditProps> = (props) => {
           </div>
           <div class="flex flex-col items-start gap-1">
             <label class="font-bold" for="picture">
-              バナー
+              {i18n()('profile.edit.banner')}
             </label>
             <input
               class="w-full rounded-md focus:border-rose-100 focus:ring-rose-300"
@@ -197,7 +199,7 @@ const ProfileEdit: Component<ProfileEditProps> = (props) => {
           </div>
           <div class="flex flex-col items-start gap-1">
             <label class="font-bold" for="name">
-              ユーザ名
+              {i18n()('profile.edit.name')}
             </label>
             <div class="flex w-full items-center gap-2">
               <span>@</span>
@@ -218,7 +220,7 @@ const ProfileEdit: Component<ProfileEditProps> = (props) => {
           </div>
           <div class="flex flex-col items-start gap-1">
             <label class="font-bold" for="name">
-              名前
+              {i18n()('profile.edit.displayName')}
             </label>
             <input
               class="w-full rounded-md focus:border-rose-100 focus:ring-rose-300"
@@ -233,7 +235,7 @@ const ProfileEdit: Component<ProfileEditProps> = (props) => {
           </div>
           <div class="flex flex-col items-start gap-1">
             <label class="font-bold" for="name">
-              自己紹介
+              {i18n()('profile.edit.about')}
             </label>
             <textarea
               class="w-full rounded-md focus:border-rose-100 focus:ring-rose-300"
@@ -246,7 +248,7 @@ const ProfileEdit: Component<ProfileEditProps> = (props) => {
           </div>
           <div class="flex flex-col items-start gap-1">
             <label class="font-bold" for="name">
-              ウェブサイト
+              {i18n()('profile.edit.website')}
             </label>
             <input
               class="w-full rounded-md focus:border-rose-100 focus:ring-rose-300"
@@ -261,7 +263,7 @@ const ProfileEdit: Component<ProfileEditProps> = (props) => {
           </div>
           <div class="flex flex-col items-start gap-1">
             <label class="font-bold" for="name">
-              ドメイン認証（NIP-05）
+              {i18n()('profile.edit.nip05')}
             </label>
             <input
               class="w-full rounded-md focus:border-rose-100 focus:ring-rose-300"
@@ -277,9 +279,9 @@ const ProfileEdit: Component<ProfileEditProps> = (props) => {
           </div>
           <div class="flex flex-col items-start gap-1">
             <label class="font-bold" for="name">
-              LNURLアドレス / ライトニングアドレス
+              {i18n()('profile.edit.lightningAddress')}
             </label>
-            <span class="text-xs">どちらか片方のみが保存されます。</span>
+            <span class="text-xs">{i18n()('profile.edit.lightningAddressDescription')}</span>
             <input
               class="w-full rounded-md focus:border-rose-100 focus:ring-rose-300"
               type="text"
@@ -294,7 +296,7 @@ const ProfileEdit: Component<ProfileEditProps> = (props) => {
           </div>
           <Show when={Object.entries(otherProperties()).length > 0}>
             <div>
-              <span class="font-bold">その他の項目</span>
+              <span class="font-bold">{i18n()('profile.edit.otherProperties')}</span>
               <div>
                 <For each={Object.entries(otherProperties())}>
                   {([key, value]) => (
@@ -313,17 +315,17 @@ const ProfileEdit: Component<ProfileEditProps> = (props) => {
               class="rounded bg-rose-300 p-2 font-bold text-white hover:bg-rose-400"
               disabled={mutation.isLoading}
             >
-              保存
+              {i18n()('profile.edit.save')}
             </button>
             <button
               type="button"
               class="rounded border border-rose-300 p-2 font-bold text-rose-300 hover:border-rose-400 hover:text-rose-400"
               onClick={() => props.onClose()}
             >
-              キャンセル
+              {i18n()('profile.edit.cancel')}
             </button>
           </div>
-          <Show when={mutation.isLoading}>保存中...</Show>
+          <Show when={mutation.isLoading}>{i18n()('profile.edit.updating')}</Show>
         </form>
       </div>
     </BasicModal>
diff --git a/src/locales/en.ts b/src/locales/en.ts
index ad12547..3437c7c 100644
--- a/src/locales/en.ts
+++ b/src/locales/en.ts
@@ -1,4 +1,5 @@
 import ja from '@/locales/ja';
+import stripMargin from '@/utils/stripMargin';
 
 export default {
   general: {
@@ -7,9 +8,16 @@ export default {
   },
   posting: {
     placeholder: "What's happening?",
+    placeholderReply: 'Post a reply',
     contentWarning: 'Content warning',
+    contentWarningReason: 'Reason of warning',
     uploadImage: 'Upload image',
     submit: 'Submit',
+    forbiddenToIncludeNsec: 'You cannot include private key (nsec).',
+    failedToUploadFile: 'Failed to upload files: {{filenames}}',
+    replyToPre: 'Reply to',
+    replyToAnd: ' and ',
+    replyToPost: '',
   },
   column: {
     home: 'Home',
@@ -49,6 +57,38 @@ export default {
     unmute: 'Unmute',
     followMyself: 'Follow myself',
     unfollowMyself: 'Unfollow myself',
+    confirmUnfollow: 'Do you really want to unfollow?',
+    confirmUpdateEvenIfEmpty: stripMargin`
+      Your follow list appears to be empty.
+
+      There is no problem if you are trying to follow for the first time.
+      Otherwise, it may be caused by poor connections to relays.
+      You should reload this page to reconnect to relays.
+      You also should make sure you have configured the same relay list as the other clients.
+
+      Do you want to continue?
+    `,
+    failedToUpdateFollowList: 'Failed to update the follow list',
+    failedToFetchLatestFollowList:
+      'Failed to fetch the latest follow list. It may be disconnected from some relays.',
+    edit: {
+      icon: 'Icon',
+      banner: 'Banner image',
+      name: 'Username',
+      displayName: 'Display Name',
+      about: 'About',
+      website: 'Website',
+      nip05: 'Domain verification (NIP-05)',
+      lightningAddress: 'LNURL address / lightning address',
+      lightningAddressDescription: 'Only one side will be saved.',
+      otherProperties: 'Other properties',
+      save: 'Save',
+      cancel: 'Cancel',
+      updating: 'updating...',
+      updateSucceeded: 'Updated successfully',
+      failedToUpdatePartially: 'Failed to update on {{count}} relays',
+      failedToUpdate: 'Failed to update on all relays',
+    },
   },
   post: {
     replyToPre: 'Replying to ',
@@ -71,6 +111,7 @@ export default {
       show: 'Click to display',
       reason: 'Reason',
     },
+    failedToFetchEvent: 'Failed to fetch event',
   },
   notification: {
     reposted: ' reposted',
diff --git a/src/locales/ja.ts b/src/locales/ja.ts
index 607e86a..53c5cb8 100644
--- a/src/locales/ja.ts
+++ b/src/locales/ja.ts
@@ -1,3 +1,5 @@
+import stripMargin from '@/utils/stripMargin';
+
 export default {
   general: {
     loading: '読み込み中',
@@ -5,9 +7,16 @@ export default {
   },
   posting: {
     placeholder: 'いまどうしてる？',
+    placeholderReply: '返信を投稿',
     contentWarning: 'コンテンツ警告を設定',
+    contentWarningReason: '警告の理由',
     uploadImage: '画像を投稿',
     submit: '投稿',
+    forbiddenToIncludeNsec: '投稿に秘密鍵(nsec)を含めることはできません。',
+    failedToUploadFile: 'ファイルのアップロードにしました: {{filenames}}',
+    replyToPre: '',
+    replyToAnd: ' と ',
+    replyToPost: 'に返信',
   },
   column: {
     home: 'ホーム',
@@ -47,6 +56,35 @@ export default {
     unmute: 'ミュート解除',
     followMyself: '自分をフォロー',
     unfollowMyself: '自分をフォロー解除',
+    confirmUnfollow: '本当にフォロー解除しますか？',
+    confirmUpdateEvenIfEmpty: stripMargin`
+      フォローリストが空のようです。初めてのフォローであれば問題ありません。
+      そうでなければ、リレーとの接続がうまくいっていない可能性があります。ページを再読み込みしてリレーと再接続してください。
+      また、他のクライアントと同じリレーを設定できているどうかご確認ください。
+
+      続行しますか？
+    `,
+    failedToUpdateFollowList: 'フォローリストの更新に失敗しました',
+    failedToFetchLatestFollowList:
+      '最新のフォローリストを取得できませんでした。リレーの接続状況が悪い可能性があります。',
+    edit: {
+      icon: 'アイコン',
+      banner: 'バナー',
+      name: 'ユーザ名',
+      displayName: 'ユーザ名',
+      about: '自己紹介',
+      website: 'ウェブサイト',
+      nip05: 'ドメイン認証（NIP-05）',
+      lightningAddress: 'LNURLアドレス / ライトニングアドレス',
+      lightningAddressDescription: 'どちらか片方のみが保存されます。',
+      otherProperties: 'その他の項目',
+      save: '更新',
+      cancel: 'キャンセル',
+      updating: '更新中...',
+      updateSucceeded: '更新しました',
+      failedToUpdatePartially: '{{count}}個のリレーで更新に失敗しました',
+      failedToUpdate: 'すべてのリレーで更新に失敗しました',
+    },
   },
   post: {
     replyToPre: '',
@@ -69,6 +107,7 @@ export default {
       show: '表示するにはクリック',
       reason: '理由',
     },
+    failedToFetchEvent: '取得に失敗しました',
   },
   notification: {
     reposted: 'がリポスト',