diff --git a/src/main/java/info/istlab/IoTP/Launcher.java b/src/main/java/info/istlab/IoTP/Launcher.java
index 09dcfaf..4690c47 100644
--- a/src/main/java/info/istlab/IoTP/Launcher.java
+++ b/src/main/java/info/istlab/IoTP/Launcher.java
@@ -190,6 +190,11 @@
                 jcbmi.addActionListener(e -> chooseSerial(e));
             }
         }
+        serialMenu.addSeparator();
+        mi = new JMenuItem("シリアルモニタをすべて閉じる");
+        mi.addActionListener(ae -> SerialWindow.disposeAll());
+        serialMenu.add(mi);
+
     }
     void chooseSerial(ActionEvent e){
         App.serialName = e.getActionCommand();