diff --git a/src/FirstGUI.java b/src/FirstGUI.java
index 5461c24..3f27dd3 100644
--- a/src/FirstGUI.java
+++ b/src/FirstGUI.java
@@ -1,6 +1,4 @@
 import java.awt.event.WindowEvent;
-import java.awt.event.WindowListener;
-
 import javax.swing.JButton;
 import javax.swing.JFrame;
 
@@ -30,6 +28,7 @@
         System.out.println("Button [" + e.getActionCommand() + "] was pressed.");
         // new MyThread().start();
         new Thread(this).start();
+        FirstGUI.rootjf.setTitle("Button was pressed");
     }
     public SelfActionJButton(String label){
         super(label);
@@ -51,6 +50,7 @@
 
 public class FirstGUI /*implements ActionListener*/ {
 
+    public static JFrame rootjf; //アプリケーションのメインのウィンドウ
     public static void main(String[] args) {
         SelfActionJButton jb = new SelfActionJButton("ボタン");
         // ActionListener( );
@@ -67,7 +67,7 @@
                 System.exit(0);
             }
         });
+        rootjf = jf;
 
     }
-
 }
diff --git a/src/SecondGUI.java b/src/SecondGUI.java
new file mode 100644
index 0000000..ab97bcb
--- /dev/null
+++ b/src/SecondGUI.java
@@ -0,0 +1,53 @@
+import javax.swing.JButton;
+import javax.swing.JFrame;
+import javax.swing.JPanel;
+
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.awt.BorderLayout;
+import java.awt.Dimension;
+public class SecondGUI extends JFrame {
+    public static JFrame rootjf;
+    public static void main(String[] args){
+        new SecondGUI();
+    }
+    public SecondGUI(){
+        super("SecondGUI");
+        setSize(300,200);
+        setVisible(true);
+        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        JPanel northP = new JPanel();
+        getContentPane().add(northP, BorderLayout.NORTH);
+        getContentPane().add(new JButton("CENTER") );
+        northP.add(new ResizeButton("label", 200, 100));
+        northP.add(new ResizeButton("label", 200, 100));
+        pack();
+        SecondGUI.rootjf = this;
+    }
+}
+
+// interface ActionListener {
+//     public void actionPerformed(ActionEvent e);
+// }
+
+class ResizeButton extends JButton implements ActionListener {
+    private int width, height;
+    ResizeButton(String label, int w, int h){
+        super(label);
+        width = w;
+        height = h;
+        addActionListener(this);
+    }
+    public Dimension getPreferredSize(){
+        return new Dimension(width, height);
+    }
+
+    @Override
+    public void actionPerformed(ActionEvent e) {
+        width += 30;
+        height += 10;
+        SecondGUI.rootjf.pack();
+
+    }
+
+}
\ No newline at end of file