diff --git a/src/main/java/info/istlab/ServerTester/App.java b/src/main/java/info/istlab/ServerTester/App.java
index b1df7db..ad8f13e 100644
--- a/src/main/java/info/istlab/ServerTester/App.java
+++ b/src/main/java/info/istlab/ServerTester/App.java
@@ -37,5 +37,7 @@
         WhiteBoardServer wb = new WhiteBoardServer(11111, "0.0.0.0");
         myhost.addPanel(new ServerPanel(wb, myhost));
 
+
+        new UDPServer().start();
     }
 }
diff --git a/src/main/java/info/istlab/ServerTester/Host.java b/src/main/java/info/istlab/ServerTester/Host.java
index fa3f4c6..4150779 100644
--- a/src/main/java/info/istlab/ServerTester/Host.java
+++ b/src/main/java/info/istlab/ServerTester/Host.java
@@ -35,6 +35,13 @@
         setJMenuBar(menuBar);
         JMenu menu = new JMenu("Menu");
         menuBar.add(menu);
+
+        JMenuItem sendItem = new JMenuItem("Send");
+        menu.add(sendItem);
+        sendItem.addActionListener(e -> {
+            new UDPClient();
+        });
+
         JMenuItem exitItem = new JMenuItem("Exit");
         menu.add(exitItem);
         exitItem.addActionListener(e -> {
diff --git a/src/main/java/info/istlab/ServerTester/UDPClient.java b/src/main/java/info/istlab/ServerTester/UDPClient.java
new file mode 100644
index 0000000..376a8d1
--- /dev/null
+++ b/src/main/java/info/istlab/ServerTester/UDPClient.java
@@ -0,0 +1,48 @@
+package info.istlab.ServerTester;
+
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+import java.net.InetAddress;
+
+public class UDPClient {
+    public static void main(String[] args) {
+    }
+    public UDPClient() {
+        DatagramSocket socket = null;
+        try {
+            // クライアントソケットを作成
+            socket = new DatagramSocket();
+            socket.setBroadcast(true);
+            InetAddress serverAddress = InetAddress.getByName("255.255.255.255");
+
+            // 送信メッセージを作成
+            String message = "こんにちは、サーバー!";
+            byte[] messageData = message.getBytes();
+
+            // データグラムパケットを作成
+            DatagramPacket packet = new DatagramPacket(
+                    messageData, messageData.length, 
+                    serverAddress, 54321
+            );
+
+            // メッセージを送信
+            socket.send(packet);
+            System.out.println("メッセージをサーバーに送信しました: " + message);
+
+            // サーバーからの応答を受信
+            byte[] buffer = new byte[1024];
+            DatagramPacket responsePacket = new DatagramPacket(buffer, buffer.length);
+            socket.receive(responsePacket);
+            
+            // 受信したデータを文字列に変換
+            String response = new String(responsePacket.getData(), 0, responsePacket.getLength());
+            System.out.println("サーバーからの応答: " + response);
+        } catch (Exception e) {
+            e.printStackTrace();
+        } finally {
+            if (socket != null && !socket.isClosed()) {
+                socket.close();
+            }
+        }
+    }
+}
diff --git a/src/main/java/info/istlab/ServerTester/UDPServer.java b/src/main/java/info/istlab/ServerTester/UDPServer.java
new file mode 100644
index 0000000..e3d3de6
--- /dev/null
+++ b/src/main/java/info/istlab/ServerTester/UDPServer.java
@@ -0,0 +1,69 @@
+package info.istlab.ServerTester;
+
+import java.io.IOException;
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+
+public class UDPServer implements Runnable {
+    Thread thread;
+    DatagramSocket socket = null;
+
+    public static void main(String[] args) {
+        new UDPServer();
+    }
+
+    public UDPServer() {
+        this(54321);
+    }
+    public UDPServer(int port) {
+        try {
+            // サーバーソケットを指定されたポートで作成
+            socket = new DatagramSocket(port);
+
+            System.out.println("[UDP] UDPサーバーがポート"+port+"で待機中...");
+            
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+    public void start(){
+        if(thread == null){
+            thread = new Thread(this);
+            thread.start();
+        }
+    }
+    public void run(){
+        byte[] buffer = new byte[1024];
+        while(thread != null){
+            try {
+                // データグラムパケットを受信
+                DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
+                socket.receive(packet);
+
+                System.out.println("[UDP] "+packet.getAddress().getHostAddress() + ":" + packet.getPort() + " からデータを受信しました。");
+
+                // 受信したデータを文字列に変換
+                String received = new String(packet.getData(), 0, packet.getLength());
+                System.out.println("[UDP] 受信したメッセージ: " + received);
+
+                // 返信メッセージを作成
+                String response = "サーバーからの応答: " + received;
+                byte[] responseData = response.getBytes();
+
+                // 返信データを送信
+                DatagramPacket responsePacket = new DatagramPacket(
+                        responseData, responseData.length,
+                        packet.getAddress(), packet.getPort());
+                socket.send(responsePacket);
+
+            } catch (IOException e) {
+                e.printStackTrace();
+                thread = null;
+            }
+        }
+        if (socket != null && !socket.isClosed()) {
+            socket.close();
+            System.out.println("[UDP] UDPサーバーを停止しました。");
+        }
+    }
+}
diff --git a/src/main/java/info/istlab/ServerTester/WhiteBoardClient.java b/src/main/java/info/istlab/ServerTester/WhiteBoardClient.java
index 6a6d77c..fd14885 100644
--- a/src/main/java/info/istlab/ServerTester/WhiteBoardClient.java
+++ b/src/main/java/info/istlab/ServerTester/WhiteBoardClient.java
@@ -11,6 +11,7 @@
 import java.io.PrintWriter;
 import java.net.InetSocketAddress;
 import java.net.Socket;
+import java.net.SocketException;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.concurrent.CopyOnWriteArrayList;
@@ -34,8 +35,6 @@
     public WhiteBoardClient(int port, String address) {
         address = address.replace("/", "");
 
-        // 指定のポートに対して,ソケットを作成します
-        // オブジェクトinstrを作り,データ読み出しを準備します
         try {
             socket = new Socket();
             socket.connect(new InetSocketAddress(address, port), 1000); // 1秒でタイムアウト
@@ -64,7 +63,7 @@
 
     @Override
     public void mouseDragged(MouseEvent e) {
-        if (e.getX()==lastx && e.getY()==lasty) {
+        if (e.getX() == lastx && e.getY() == lasty) {
             return;
         }
         tmpStroke.add(e.getPoint());
@@ -118,7 +117,7 @@
     synchronized public void paintComponent(Graphics g) {
         super.paintComponent(g);
         Iterator<String> it = points.iterator();
-        while(it.hasNext()) {
+        while (it.hasNext()) {
             int[][] points = MyJSON.fromJSON(it.next());
             for (int[] p : points) {
                 int x = p[0];
@@ -152,15 +151,18 @@
             } catch (IOException e1) {
                 e1.printStackTrace();
                 thread = null;
+                if (e1 instanceof SocketException) {
+                    System.err.println("サーバとの接続が切れました (Connection reset)");
+                }
             }
         }
     }
 }
 
-/** 
+/**
  * 上記のrun()において、メッセージを送信しないと reader.readLine() で止まってしまって画面描画されないので、
  * 1秒ごとに強制的に再描画するためのスレッド
- * */
+ */
 class RepaintClient implements Runnable {
     private WhiteBoardClient client;
     Thread thread;