diff --git a/apps/client/src/app.tsx b/apps/client/src/app.tsx
index 08b1b54..a44fa3e 100644
--- a/apps/client/src/app.tsx
+++ b/apps/client/src/app.tsx
@@ -9,14 +9,15 @@
 import { appConsts } from "@repo/shared";
 
 export default function App() {
-  const { scenePhase, room, myId, joinErrorMessage } = useAppFlow();
+  const { scenePhase, room, myId, joinErrorMessage, isJoining, requestJoin } = useAppFlow();
 
   // タイトル画面分岐
   if (scenePhase === appConsts.ScenePhase.TITLE) {
     return (
       <TitleScene
-        onJoin={(payload) => socketManager.title.joinRoom(payload)}
+        onJoin={requestJoin}
         joinErrorMessage={joinErrorMessage}
+        isJoining={isJoining}
       />
     );
   }
diff --git a/apps/client/src/hooks/useAppFlow.ts b/apps/client/src/hooks/useAppFlow.ts
index 6fe6ae8..db815c9 100644
--- a/apps/client/src/hooks/useAppFlow.ts
+++ b/apps/client/src/hooks/useAppFlow.ts
@@ -1,6 +1,6 @@
-import { useEffect, useState } from "react";
+import { useEffect, useRef, useState } from "react";
 import { socketManager } from "@client/network/SocketManager";
-import { appConsts } from "@repo/shared";
+import { appConsts, config } from "@repo/shared";
 import type { appTypes, roomTypes } from "@repo/shared";
 
 type AppFlowState = {
@@ -8,6 +8,8 @@
   room: roomTypes.Room | null;
   myId: string | null;
   joinErrorMessage: string | null;
+  isJoining: boolean;
+  requestJoin: (payload: roomTypes.JoinRoomPayload) => void;
 };
 
 export const useAppFlow = (): AppFlowState => {
@@ -15,17 +17,44 @@
   const [room, setRoom] = useState<roomTypes.Room | null>(null);
   const [myId, setMyId] = useState<string | null>(null);
   const [joinErrorMessage, setJoinErrorMessage] = useState<string | null>(null);
+  const [isJoining, setIsJoining] = useState(false);
+  const joinTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+
+  const clearJoinTimeout = () => {
+    if (!joinTimeoutRef.current) {
+      return;
+    }
+
+    clearTimeout(joinTimeoutRef.current);
+    joinTimeoutRef.current = null;
+  };
+
+  const requestJoin = (payload: roomTypes.JoinRoomPayload) => {
+    clearJoinTimeout();
+    setJoinErrorMessage(null);
+    setIsJoining(true);
+    joinTimeoutRef.current = setTimeout(() => {
+      setIsJoining(false);
+      setJoinErrorMessage("参加要求がタイムアウトしました，もう一度お試しください");
+      joinTimeoutRef.current = null;
+    }, config.GAME_CONFIG.JOIN_REQUEST_TIMEOUT_MS);
+    socketManager.title.joinRoom(payload);
+  };
 
   useEffect(() => {
     const handleConnect = (id: string) => {
       setMyId(id);
     };
     const handleRoomUpdate = (updatedRoom: roomTypes.Room) => {
+      clearJoinTimeout();
       setRoom(updatedRoom);
+      setIsJoining(false);
       setJoinErrorMessage(null);
       setScenePhase(appConsts.ScenePhase.LOBBY);
     };
     const handleJoinRejected = (payload: roomTypes.JoinRoomRejectedPayload) => {
+      clearJoinTimeout();
+      setIsJoining(false);
       if (payload.reason === "full") {
         setJoinErrorMessage(`ルーム ${payload.roomId} は満員です`);
       }
@@ -40,6 +69,7 @@
     socketManager.game.onGameStart(handleGameStart);
 
     return () => {
+      clearJoinTimeout();
       socketManager.common.offConnect(handleConnect);
       socketManager.title.offJoinRejected(handleJoinRejected);
       socketManager.lobby.offRoomUpdate(handleRoomUpdate);
@@ -47,5 +77,5 @@
     };
   }, []);
 
-  return { scenePhase, room, myId, joinErrorMessage };
+  return { scenePhase, room, myId, joinErrorMessage, isJoining, requestJoin };
 };
diff --git a/apps/client/src/scenes/title/TitleScene.tsx b/apps/client/src/scenes/title/TitleScene.tsx
index cec2fdc..ffb2328 100644
--- a/apps/client/src/scenes/title/TitleScene.tsx
+++ b/apps/client/src/scenes/title/TitleScene.tsx
@@ -7,9 +7,11 @@
   onJoin: (payload: roomTypes.JoinRoomPayload) => void;
   // 入室失敗時の表示メッセージ
   joinErrorMessage: string | null;
+  // 入室リクエスト送信中フラグ
+  isJoining: boolean;
 };
 
-export const TitleScene = ({ onJoin, joinErrorMessage }: Props) => {
+export const TitleScene = ({ onJoin, joinErrorMessage, isJoining }: Props) => {
   // プレイヤー名入力値
   const [playerName, setPlayerName] = useState("");
   // ルームID入力値
@@ -46,12 +48,12 @@
       
       <button
         onClick={handleJoin}
-        disabled={!canJoin}
+        disabled={!canJoin || isJoining}
         style={{
           padding: "15px 30px",
           fontSize: "1.2rem",
-          cursor: !canJoin ? "not-allowed" : "pointer",
-          backgroundColor: !canJoin ? "#555" : "#3b82f6",
+          cursor: !canJoin || isJoining ? "not-allowed" : "pointer",
+          backgroundColor: !canJoin || isJoining ? "#555" : "#3b82f6",
           color: "white",
           border: "none",
           borderRadius: "5px",
@@ -59,7 +61,7 @@
           fontWeight: "bold"
         }}
       >
-        ルームに入る / 作る
+        {isJoining ? "参加中..." : "ルームに入る / 作る"}
       </button>
 
       {joinErrorMessage && (
diff --git a/packages/shared/src/config/gameConfig.ts b/packages/shared/src/config/gameConfig.ts
index bc2a755..eac31d5 100644
--- a/packages/shared/src/config/gameConfig.ts
+++ b/packages/shared/src/config/gameConfig.ts
@@ -5,6 +5,7 @@
 
   // UI表示更新設定
   TIMER_DISPLAY_UPDATE_MS: 250, // 残り時間表示の更新間隔（ms）
+  JOIN_REQUEST_TIMEOUT_MS: 8000, // ルーム参加要求の待機タイムアウト（ms）
 
   // ネットワーク・描画補間設定
   PLAYER_POSITION_UPDATE_MS: 50,  // 座標送信間隔（20Hz）