diff --git a/apps/client/src/app.tsx b/apps/client/src/app.tsx
index df5cec0..ea6e82f 100644
--- a/apps/client/src/app.tsx
+++ b/apps/client/src/app.tsx
@@ -4,12 +4,12 @@
 // シーン（画面）コンポーネント
 import { TitleScene } from "./scenes/TitleScene";
 import { LobbyScene } from "./scenes/LobbyScene";
-import { GameScene } from "./scenes/GameScene"; // 👈 追加
+import { GameScene } from "./scenes/GameScene";
 
-import type { Room } from "@repo/shared/src/types/room";
+import { GameState, type Room } from "@repo/shared/src/types/room";
 
 export default function App() {
-  const [gameState, setGameState] = useState<"title" | "lobby" | "playing">("title");
+  const [gameState, setGameState] = useState<GameState>(GameState.TITLE);
   const [room, setRoom] = useState<Room | null>(null);
   const [myId, setMyId] = useState<string | null>(null);
 
@@ -17,17 +17,17 @@
     socketClient.onConnect((id) => setMyId(id));
     socketClient.onRoomUpdate((updatedRoom) => {
       setRoom(updatedRoom);
-      setGameState("lobby");
+      setGameState(GameState.LOBBY);
     });
-    socketClient.onGameStart(() => setGameState("playing"));
+    socketClient.onGameStart(() => setGameState(GameState.PLAYING));
   }, []);
 
   // レンダリング分岐
-  if (gameState === "title") {
+  if (gameState === GameState.TITLE) {
     return <TitleScene onJoin={(payload) => socketClient.joinRoom(payload.roomId, payload.playerName)} />;
   }
   
-  if (gameState === "lobby") {
+  if (gameState === GameState.LOBBY) {
     return <LobbyScene room={room} myId={myId} onStart={() => socketClient.startGame()} />;
   }
 
diff --git a/apps/server/src/network/SocketManager.ts b/apps/server/src/network/SocketManager.ts
index 5cc23da..a32636d 100644
--- a/apps/server/src/network/SocketManager.ts
+++ b/apps/server/src/network/SocketManager.ts
@@ -2,7 +2,7 @@
 import { Server, Socket } from "socket.io";
 import { GameManager } from "../managers/GameManager.js";
 // shared側の型をインポート（※パスは実際の環境に合わせて修正してください）
-import type { Room } from "@repo/shared/src/types/room";
+import { Room, RoomStatus } from "@repo/shared/src/types/room";
 import { SocketEvents } from "@repo/shared/src/protocol/events";
 
 type RoomPlayer = Room["players"][0];
@@ -40,7 +40,7 @@
             roomId: roomId,
             ownerId: socket.id, // 最初に作った人がオーナー
             players: [],
-            status: 'waiting',
+            status: RoomStatus.WAITING,
             maxPlayers: 4
           };
           this.rooms.set(roomId, room);
@@ -63,7 +63,7 @@
       socket.on(SocketEvents.START_GAME, () => {
         for (const [roomId, room] of this.rooms.entries()) {
           if (room.ownerId === socket.id) {
-            room.status = 'playing';
+            room.status = RoomStatus.PLAYING;
             
             // 🎮 全員を GameManager に追加する
             room.players.forEach(p => {
diff --git a/packages/shared/src/types/room.ts b/packages/shared/src/types/room.ts
index a952fa9..994fd39 100644
--- a/packages/shared/src/types/room.ts
+++ b/packages/shared/src/types/room.ts
@@ -1,21 +1,35 @@
+// 🌟 追加: アプリの画面遷移状態を定義
+export const GameState = {
+  TITLE: 'title',
+  LOBBY: 'lobby',
+  PLAYING: 'playing',
+} as const;
+export type GameState = typeof GameState[keyof typeof GameState];
+
+// 🌟 追加・修正: ルームの進行状態を文字列から定数オブジェクトに変更
+export const RoomStatus = {
+  WAITING: 'waiting',
+  PLAYING: 'playing',
+  RESULT: 'result',
+} as const;
+export type RoomStatus = typeof RoomStatus[keyof typeof RoomStatus];
+
 export interface Player {
-  id: string;        // Socket ID
-  name: string;      // ユーザーが入力した名前
-  isOwner: boolean;  // ルームオーナーかどうか
-  isReady: boolean;  // 準備完了状態
+  id: string;
+  name: string;
+  isOwner: boolean;
+  isReady: boolean;
 }
 
-export type RoomStatus = 'waiting' | 'playing' | 'result';
-
 export interface Room {
-  roomId: string;      // ルームを識別するID
-  ownerId: string;     // オーナーのPlayer ID
-  players: Player[];   // 参加中のプレイヤーリスト
-  status: RoomStatus;  // 現在の状態
-  maxPlayers: number;  // 最大参加人数（デフォルト4など）
+  roomId: string;
+  ownerId: string;
+  players: Player[];
+  status: RoomStatus;  // 👈 ここで上記の型を使用する
+  maxPlayers: number;
 }
 
 export interface JoinRoomPayload {
   roomId: string;
   playerName: string;
-}
+}
\ No newline at end of file