diff --git a/README.md b/README.md
index a9b8f8d..a6261e4 100644
--- a/README.md
+++ b/README.md
@@ -36,9 +36,13 @@ Note that `joint_ids` parameters must be splited by `,`.
   <param name="usb_port">/dev/ttyUSB0</param>
   <param name="baud_rate">1000000</param>
   <!-- <param name="use_dummy">true</param> -->
+  <param name="extended_mode">false</param> <!-- Set true if you use the extended position mode of Dynamixel motors -->
 </hardware>
 ```
 
+Note that the `extended_mode` parameter is optional and set to `false` by default.
+If you use the extended position (multi turn) mode of Dynamixel motors, set it to `true`.
+
 - Terminal 1
 
 Launch the `ros2_control` manager for the OpenManipulator-X.