diff --git a/apps/server/src/entities/Player.ts b/apps/server/src/entities/Player.ts
new file mode 100644
index 0000000..da5e973
--- /dev/null
+++ b/apps/server/src/entities/Player.ts
@@ -0,0 +1,15 @@
+// src/entities/Player.ts
+export class Player {
+  public id: string;
+  public x: number;
+  public y: number;
+  public color: string;
+
+  constructor(id: string) {
+    this.id = id;
+    this.x = 0;
+    this.y = 0;
+    // ランダムな色をつけるとおしゃれです
+    this.color = '#' + Math.floor(Math.random()*16777215).toString(16);
+  }
+}
\ No newline at end of file
diff --git a/apps/server/src/index.ts b/apps/server/src/index.ts
index 92df8af..bc29276 100644
--- a/apps/server/src/index.ts
+++ b/apps/server/src/index.ts
@@ -1 +1,30 @@
-console.log("Server is running!");
\ No newline at end of file
+// src/index.ts
+import { Server } from "socket.io";
+import { createServer } from "http"; // Node.js標準のHTTPサーバー
+import { GameManager } from "./managers/GameManager.js";
+import { SocketManager } from "./network/SocketManager.js";
+
+const PORT = 3000;
+
+// HTTPサーバーとSocket.ioサーバーの作成
+const httpServer = createServer();
+const io = new Server(httpServer, {
+  cors: {
+    origin: "*", // 開発用：どこからでも許可
+    methods: ["GET", "POST"]
+  },
+});
+
+// ゲームマネージャーと通信マネージャーの起動
+const gameManager = new GameManager();
+const socketManager = new SocketManager(io, gameManager);
+
+socketManager.initialize();
+
+// サーバー起動
+httpServer.listen(PORT, () => {
+  console.log(`
+  🚀 Server is running on port ${PORT}
+  waiting for connections...
+  `);
+});
\ No newline at end of file
diff --git a/apps/server/src/managers/GameManager.ts b/apps/server/src/managers/GameManager.ts
new file mode 100644
index 0000000..a69454a
--- /dev/null
+++ b/apps/server/src/managers/GameManager.ts
@@ -0,0 +1,38 @@
+// src/managers/GameManager.ts
+import { Player } from "../entities/Player.js";
+
+export class GameManager {
+  // IDをキーにしてプレイヤーを保存する
+  private players: Map<string, Player>;
+
+  constructor() {
+    this.players = new Map();
+  }
+
+  // プレイヤー追加
+  addPlayer(id: string): Player {
+    const player = new Player(id);
+    this.players.set(id, player);
+    return player;
+  }
+
+  // プレイヤー削除
+  removePlayer(id: string) {
+    this.players.delete(id);
+  }
+
+  // プレイヤー移動
+  movePlayer(id: string, x: number, y: number) {
+    const player = this.players.get(id);
+    if (player) {
+      player.x = x;
+      player.y = y;
+    }
+  }
+
+  // 全プレイヤーのリストを返す（通信で送るため）
+  getAllPlayers() {
+    // Mapを配列({id, x, y, color}[])に変換
+    return Array.from(this.players.values());
+  }
+}
\ No newline at end of file
diff --git a/apps/server/src/network/SocketManager.ts b/apps/server/src/network/SocketManager.ts
new file mode 100644
index 0000000..0811091
--- /dev/null
+++ b/apps/server/src/network/SocketManager.ts
@@ -0,0 +1,47 @@
+// src/network/SocketManager.ts
+import { Server, Socket } from "socket.io";
+import { GameManager } from "../managers/GameManager.js";
+
+export class SocketManager {
+  private io: Server;
+  private gameManager: GameManager;
+
+  constructor(io: Server, gameManager: GameManager) {
+    this.io = io;
+    this.gameManager = gameManager;
+  }
+
+  public initialize() {
+    this.io.on("connection", (socket: Socket) => {
+      console.log(`✅ User connected: ${socket.id}`);
+
+      // 1. ゲームにプレイヤーを追加
+      const player = this.gameManager.addPlayer(socket.id);
+
+      // 2. 参加した本人に「現在の全プレイヤー」を教える
+      socket.emit("current_players", this.gameManager.getAllPlayers());
+
+      // 3. 他のみんなに「新しい人が来たよ」と教える
+      socket.broadcast.emit("new_player", player);
+
+      // --- イベント受信 ---
+
+      // 移動データが来た時
+      socket.on("move", (data: { x: number; y: number }) => {
+        // マネージャーの状態を更新
+        this.gameManager.movePlayer(socket.id, data.x, data.y);
+        
+        // 全員に位置情報を配信
+        // (人数が増えたらここを最適化しますが、まずはこれでOK)
+        this.io.emit("update_player", { id: socket.id, x: data.x, y: data.y });
+      });
+
+      // 切断した時
+      socket.on("disconnect", () => {
+        console.log(`❌ User disconnected: ${socket.id}`);
+        this.gameManager.removePlayer(socket.id);
+        this.io.emit("remove_player", socket.id);
+      });
+    });
+  }
+}
\ No newline at end of file