diff --git a/src/main/java/info/istlab/ServerTester/AddPanel.java b/src/main/java/info/istlab/ServerTester/AddPanel.java
index 604b9d4..de809a4 100644
--- a/src/main/java/info/istlab/ServerTester/AddPanel.java
+++ b/src/main/java/info/istlab/ServerTester/AddPanel.java
@@ -121,7 +121,7 @@
                     System.out.println("IP Address: " + address.getHostAddress());
                     System.out.println("Subnet Mask: " + subnetMaskString);
                     System.out.println("Network Address: " + networkAddressString);
-                    UDPClient.networkAddress = networkAddressString;
+                    App.ipAddr = address.getHostAddress();
                     addresses.add(address.getHostAddress());
                 }
             }
diff --git a/src/main/java/info/istlab/ServerTester/App.java b/src/main/java/info/istlab/ServerTester/App.java
index 39f5f25..2eda36a 100644
--- a/src/main/java/info/istlab/ServerTester/App.java
+++ b/src/main/java/info/istlab/ServerTester/App.java
@@ -7,6 +7,7 @@
     public static String userhome;
     public static String userdir;
     public static boolean isJAR = false;
+    public static String ipAddr;
 
     static {
         String os = System.getProperty("os.name").toLowerCase();
@@ -67,6 +68,8 @@
         }
 
         // 近隣のホスト情報を集めるUDPサーバ
-        myhost.setUdpServer(new UDPServer(54320));
+        // myhost.setUdpServer(new UDPServer(54320));
+        new MulticastSender();
+        new MulticastReceiver();
     }
 }
diff --git a/src/main/java/info/istlab/ServerTester/MulticastReceiver.java b/src/main/java/info/istlab/ServerTester/MulticastReceiver.java
new file mode 100644
index 0000000..0e311e1
--- /dev/null
+++ b/src/main/java/info/istlab/ServerTester/MulticastReceiver.java
@@ -0,0 +1,37 @@
+package info.istlab.ServerTester;
+
+import java.io.IOException;
+import java.net.DatagramPacket;
+import java.net.InetAddress;
+import java.net.MulticastSocket;
+
+public class MulticastReceiver implements Runnable{
+    Thread thread;
+    MulticastSocket socket;
+    public MulticastReceiver() {
+        try {
+            socket = new MulticastSocket(54320);
+            InetAddress group = InetAddress.getByName("224.0.0.1");
+            socket.joinGroup(group);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        thread = new Thread(this);
+        thread.start();
+    }
+
+    public void run(){
+        while(thread != null){
+            byte[] buffer = new byte[1024];
+            DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
+            try {
+                socket.receive(packet);
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+            String message = new String(packet.getData(), 0, packet.getLength());
+            System.out.println("受信: " + message);
+
+        }
+    }
+}
diff --git a/src/main/java/info/istlab/ServerTester/MulticastSender.java b/src/main/java/info/istlab/ServerTester/MulticastSender.java
new file mode 100644
index 0000000..ebcd863
--- /dev/null
+++ b/src/main/java/info/istlab/ServerTester/MulticastSender.java
@@ -0,0 +1,50 @@
+package info.istlab.ServerTester;
+
+import java.io.IOException;
+import java.net.DatagramPacket;
+import java.net.InetAddress;
+import java.net.MulticastSocket;
+import java.util.Random;
+
+public class MulticastSender implements Runnable {
+    Thread thread;
+    MulticastSocket socket = null;
+    public String message;
+    String multicastAddress = "224.0.0.1"; // マルチキャストアドレス
+    public int port = 54320;
+    InetAddress group;
+    
+    public MulticastSender() {
+        try {
+            socket = new MulticastSocket();
+            group = InetAddress.getByName(multicastAddress);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        thread = new Thread(this);
+        thread.start();
+    }
+
+    @Override
+    public void run() {
+        Random rand = new Random();
+        while(thread != null){
+            String message = "from "+App.ipAddr + " "+rand.nextInt(100) ;
+            byte[] data = message.getBytes();
+            DatagramPacket packet = new DatagramPacket(data, data.length, group, port);
+            try {
+                socket.send(packet);
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+
+            try {
+                Thread.sleep(2000);
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }
+
+    }
+
+}