diff --git a/server/.env.example b/server/.env.example
index d68e190e72..d9b8986741 100644
--- a/server/.env.example
+++ b/server/.env.example
@@ -1,6 +1,8 @@
 # General
 PORT=8080
 REEARTH_DB=mongodb://localhost
+REEARTH_DB_ACCOUNT=reearth # for account database
+REEARTH_DB_VIS=reearth # for visualizer database
 REEARTH_HOST=https://localhost:8080
 REEARTH_HOST_WEB=https://localhost:3000
 REEARTH_ASSETBASEURL=https://localhost:8080/assets