diff --git a/README.md b/README.md
index 00fa9a7..0fdb76e 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,13 @@ kintone Plug-in SDK
 
 This SDK includes kintone plug-in packaging tool.
 
+## package.sh is now deprecated!
+
+`package.sh` has been deprecated.
+
+Please use [@kintone/plugin-packer](https://www.npmjs.com/package/@kintone/plugin-packer) instead.
+It requires [Node.js](https://nodejs.org/).
+
 ## Requirement
 
 * A bash shell
diff --git a/package.sh b/package.sh
index 3fda039..580f598 100755
--- a/package.sh
+++ b/package.sh
@@ -1,6 +1,15 @@
 #!/bin/sh
 BASE_DIR=$(cd $(dirname $0); pwd)
 
+echo ""
+echo "WARNING!"
+echo "--------------------------------"
+echo "package.sh has been deprecated."
+echo "Please use @kintone/plugin-packer instead."
+echo "https://www.npmjs.com/package/@kintone/plugin-packer"
+echo "--------------------------------"
+echo ""
+
 if [ $# -lt 1 ]; then
     echo "usage: $0 PLUGIN_DIR [PRIVATE_KEY_FILE]"
     exit 1