diff --git a/README.md b/README.md
index 3ce90d3..a6a7fb3 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,7 @@
 # real_tsudanuma2-3_sim
+## caution
+world file of stable version is tsudanuma2-3_v2.3.3.world
+
 ## install
 ~~~
 cd ~/catkin_ws/src