diff --git a/src/app/projects/[projectId]/components/newChat/NewChat.tsx b/src/app/projects/[projectId]/components/newChat/NewChat.tsx
index 60bfa85..a12a407 100644
--- a/src/app/projects/[projectId]/components/newChat/NewChat.tsx
+++ b/src/app/projects/[projectId]/components/newChat/NewChat.tsx
@@ -119,7 +119,7 @@ export const NewChat: FC<{
             {startNewChat.isPending ? (
               <>
                 <LoaderIcon className="w-4 h-4 animate-spin" />
-                Starting...
+                Starting... This may take a while.
               </>
             ) : (
               <>
diff --git a/src/app/projects/[projectId]/sessions/[sessionId]/components/SessionPageContent.tsx b/src/app/projects/[projectId]/sessions/[sessionId]/components/SessionPageContent.tsx
index dd6f483..1fd7805 100644
--- a/src/app/projects/[projectId]/sessions/[sessionId]/components/SessionPageContent.tsx
+++ b/src/app/projects/[projectId]/sessions/[sessionId]/components/SessionPageContent.tsx
@@ -1,10 +1,12 @@
 "use client";
 
-import { ArrowLeftIcon, LoaderIcon } from "lucide-react";
+import { useMutation } from "@tanstack/react-query";
+import { ArrowLeftIcon, LoaderIcon, XIcon } from "lucide-react";
 import Link from "next/link";
 import type { FC } from "react";
 import { useEffect, useRef, useState } from "react";
 import { Button } from "@/components/ui/button";
+import { honoClient } from "../../../../../../lib/api/client";
 import { firstCommandToTitle } from "../../../services/firstCommandToTitle";
 import { useIsResummingTask } from "../hooks/useIsResummingTask";
 import { useSession } from "../hooks/useSession";
@@ -21,6 +23,20 @@ export const SessionPageContent: FC<{
     sessionId,
   );
 
+  const abortTask = useMutation({
+    mutationFn: async (sessionId: string) => {
+      const response = await honoClient.api.tasks.abort.$post({
+        json: { sessionId },
+      });
+
+      if (!response.ok) {
+        throw new Error(response.statusText);
+      }
+
+      return response.json();
+    },
+  });
+
   const { isResummingTask } = useIsResummingTask(sessionId);
 
   const [previouConversationLength, setPreviouConversationLength] = useState(0);
@@ -77,6 +93,16 @@ export const SessionPageContent: FC<{
                       Conversation is being resumed...
                     </p>
                   </div>
+                  <Button
+                    variant="ghost"
+                    size="sm"
+                    onClick={() => {
+                      abortTask.mutate(sessionId);
+                    }}
+                  >
+                    <XIcon className="w-4 h-4" />
+                    Abort
+                  </Button>
                 </div>
               )}
 
diff --git a/src/app/projects/[projectId]/sessions/[sessionId]/components/resumeChat/ResumeChat.tsx b/src/app/projects/[projectId]/sessions/[sessionId]/components/resumeChat/ResumeChat.tsx
index 9bed06a..f118ff4 100644
--- a/src/app/projects/[projectId]/sessions/[sessionId]/components/resumeChat/ResumeChat.tsx
+++ b/src/app/projects/[projectId]/sessions/[sessionId]/components/resumeChat/ResumeChat.tsx
@@ -1,4 +1,4 @@
-import { useMutation } from "@tanstack/react-query";
+import { useMutation, useQueryClient } from "@tanstack/react-query";
 import {
   AlertCircleIcon,
   LoaderIcon,
@@ -29,6 +29,7 @@ export const ResumeChat: FC<{
 }> = ({ projectId, sessionId }) => {
   const router = useRouter();
   const textareaRef = useRef<HTMLTextAreaElement>(null);
+  const queryClient = useQueryClient();
 
   const resumeChat = useMutation({
     mutationFn: async (options: { message: string }) => {
@@ -47,6 +48,7 @@ export const ResumeChat: FC<{
     },
     onSuccess: (response) => {
       setMessage("");
+      queryClient.invalidateQueries({ queryKey: ["runningTasks"] });
       router.push(
         `/projects/${projectId}/sessions/${response.nextSessionId}#message-${response.userMessageId}`,
       );
diff --git a/src/server/hono/route.ts b/src/server/hono/route.ts
index 3ae8424..9d1da73 100644
--- a/src/server/hono/route.ts
+++ b/src/server/hono/route.ts
@@ -228,6 +228,16 @@ export const routes = (app: HonoAppType) => {
         return c.json({ runningTasks: taskController.runningTasks });
       })
 
+      .post(
+        "/tasks/abort",
+        zValidator("json", z.object({ sessionId: z.string() })),
+        async (c) => {
+          const { sessionId } = c.req.valid("json");
+          taskController.abortTask(sessionId);
+          return c.json({ message: "Task aborted" });
+        },
+      )
+
       .get("/events/state_changes", async (c) => {
         return streamSSE(
           c,
diff --git a/src/server/service/claude-code/ClaudeCodeTaskController.ts b/src/server/service/claude-code/ClaudeCodeTaskController.ts
index e14805c..6ff33be 100644
--- a/src/server/service/claude-code/ClaudeCodeTaskController.ts
+++ b/src/server/service/claude-code/ClaudeCodeTaskController.ts
@@ -21,6 +21,7 @@ type RunningClaudeCodeTask = BaseClaudeCodeTask & {
   status: "running";
   nextSessionId: string;
   userMessageId: string;
+  abortController: AbortController;
 };
 
 type CompletedClaudeCodeTask = BaseClaudeCodeTask & {
@@ -104,6 +105,8 @@ export class ClaudeCodeTaskController {
 
     const handleTask = async () => {
       try {
+        const abortController = new AbortController();
+
         for await (const message of query({
           prompt: task.message,
           options: {
@@ -111,6 +114,7 @@ export class ClaudeCodeTaskController {
             cwd: task.cwd,
             pathToClaudeCodeExecutable: this.pathToClaudeCodeExecutable,
             permissionMode: "bypassPermissions",
+            abortController,
           },
         })) {
           // 初回の sysmte message だとまだ history ファイルが作成されていないので
@@ -124,6 +128,7 @@ export class ClaudeCodeTaskController {
               status: "running",
               nextSessionId: message.session_id,
               userMessageId: message.uuid,
+              abortController,
             };
             this.updateExistingTask(runningTask);
             runningTaskResolve(runningTask);
@@ -167,4 +172,26 @@ export class ClaudeCodeTaskController {
 
     return runningTaskPromise;
   }
+
+  public abortTask(sessionId: string) {
+    const task = this.tasks
+      .filter((task) => task.status === "running")
+      .find((task) => task.nextSessionId === sessionId);
+    if (!task) {
+      throw new Error("Running Task not found");
+    }
+
+    task.abortController.abort();
+    this.updateExistingTask({
+      id: task.id,
+      status: "failed",
+      cwd: task.cwd,
+      message: task.message,
+      onMessageHandlers: task.onMessageHandlers,
+      projectId: task.projectId,
+      nextSessionId: task.nextSessionId,
+      sessionId: task.sessionId,
+      userMessageId: task.userMessageId,
+    });
+  }
 }