diff --git a/src/main/java/info/istlab/IoTP/MqttWindow.java b/src/main/java/info/istlab/IoTP/MqttWindow.java
index c067002..02d0dac 100644
--- a/src/main/java/info/istlab/IoTP/MqttWindow.java
+++ b/src/main/java/info/istlab/IoTP/MqttWindow.java
@@ -16,6 +16,7 @@
 import javax.swing.BoxLayout;
 import javax.swing.JButton;
 import javax.swing.JFrame;
+import javax.swing.JOptionPane;
 import javax.swing.JPanel;
 import javax.swing.JScrollPane;
 import javax.swing.JTextArea;
@@ -26,7 +27,7 @@
 import org.eclipse.paho.client.mqttv3.MqttException;
 import org.eclipse.paho.client.mqttv3.MqttMessage;
 
-public class MqttWindow extends JFrame implements ActionListener, WindowListener, MqttCallback {
+public class MqttWindow extends JFrame implements ActionListener, WindowListener, MqttCallback, Runnable {
     static MqttWindow theMqttWindow;
     JTextField jtf;
     JTextArea jta;
@@ -38,9 +39,11 @@
     JButton connectB;
     MqttSubscriber subscriber;
 
-    public static MqttWindow create(){
-        if (theMqttWindow != null) return theMqttWindow;
-        else theMqttWindow = new MqttWindow();
+    public static MqttWindow create() {
+        if (theMqttWindow != null)
+            return theMqttWindow;
+        else
+            theMqttWindow = new MqttWindow();
         return theMqttWindow;
     }
 
@@ -61,7 +64,8 @@
         JPanel settingP = new JPanel();
         settingP.setLayout(new BoxLayout(settingP, BoxLayout.Y_AXIS));
         JPanel v01p = new JPanel(new BorderLayout());
-        v01p.setBorder(BorderFactory.createTitledBorder("Broker ( ex. 192.168.11.11 | mqtt.istlab.info ) and port ( ex. 1883 )"));
+        v01p.setBorder(BorderFactory
+                .createTitledBorder("Broker ( ex. 192.168.11.11 | mqtt.istlab.info ) and port ( ex. 1883 )"));
         v01p.add(brokerjtf, BorderLayout.CENTER);
         v01p.add(brokerportjtf, BorderLayout.EAST);
         settingP.add(v01p);
@@ -120,19 +124,35 @@
         // jta.requestFocus();
         appendToJTA("まだ接続していません。Topicを設定してConnectをおしてください。\n");
     }
+    @Override
+    public void run() {
+        subscriber = new MqttSubscriber(brokerjtf.getText(), brokerportjtf.getText(), topicjtf.getText(), this);
+        jta.setBackground(Color.YELLOW);
+        appendToJTA("Try Connecting to broker: tcp://" + brokerjtf.getText() + ":" + brokerportjtf.getText() + ".\n");
+        try {
+            subscriber.subscribe();
+        } catch (MqttException | InterruptedException e1) {
+            e1.printStackTrace();
+            appendToJTA("接続できませんでした。\n");
+            jta.setBackground(Color.magenta);
+            thread = null;
+            return;
+        }
+        appendToJTA("Connected.\n");
+        jta.setBackground(Color.white);
+        topicjtf.setEditable(false);
+        connectB.setText("Disconnect");    
+    }
+
 
     private void connect(ActionEvent e) {
         if (e.getActionCommand().equals("Connect")) {
-            subscriber = new MqttSubscriber(brokerjtf.getText(), brokerportjtf.getText(), topicjtf.getText(), this);
-            try {
-                subscriber.subscribe();
-            } catch (MqttException | InterruptedException e1) {
-                e1.printStackTrace();
+            if (thread != null) {
+                JOptionPane.showMessageDialog(this, "まだ接続試行中です...");
+                return;
             }
-            appendToJTA("Connected.\n");
-            jta.setBackground(Color.white);
-            topicjtf.setEditable(false);
-            connectB.setText("Disconnect");
+            thread = new Thread(this);
+            thread.start();
         } else if (e.getActionCommand().equals("Disconnect")) {
             try {
                 subscriber.unsubscribe();
@@ -145,6 +165,7 @@
                 topicjtf.setEditable(true);
             }
             connectB.setText("Connect");
+            thread = null;
         }
     }
 
@@ -180,7 +201,7 @@
             if (message.length() > 0) {
                 // Topic name check
                 String topic = topicjtf.getText();
-                if ( topic.contains("#") || topic.contains("+") ){
+                if (topic.contains("#") || topic.contains("+")) {
                     appendToJTA("Publishするとき、Topic にワイルドカード文字 #+ を含めることはできません。");
                     return;
                 }
@@ -234,7 +255,7 @@
         }
         connectB.setText("Connect");
         MqttWindow.theMqttWindow = null;
-        if (Launcher.theapp == null)
+        if (Launcher.theapp == null || !Launcher.theapp.isVisible())
             System.exit(0);
         else
             dispose();
@@ -294,4 +315,5 @@
     public void deliveryComplete(IMqttDeliveryToken token) {
         throw new UnsupportedOperationException("Unimplemented method 'deliveryComplete'");
     }
+
 }