diff --git a/notify/slack_app.sh b/notify/slack_app.sh
new file mode 100755
index 00000000..84d4733a
--- /dev/null
+++ b/notify/slack_app.sh
@@ -0,0 +1,45 @@
+#!/usr/bin/env sh
+
+#Support Slack APP notifications
+
+#SLACK_APP_CHANNEL=""
+#SLACK_APP_TOKEN=""
+
+slack_app_send() {
+  _subject="$1"
+  _content="$2"
+  _statusCode="$3" #0: success, 1: error 2($RENEW_SKIP): skipped
+  _debug "_statusCode" "$_statusCode"
+
+  SLACK_APP_CHANNEL="${SLACK_APP_CHANNEL:-$(_readaccountconf_mutable SLACK_APP_CHANNEL)}"
+  if [ -n "$SLACK_APP_CHANNEL" ]; then
+    _saveaccountconf_mutable SLACK_APP_CHANNEL "$SLACK_APP_CHANNEL"
+  fi
+
+  SLACK_APP_TOKEN="${SLACK_APP_TOKEN:-$(_readaccountconf_mutable SLACK_APP_TOKEN)}"
+  if [ -n "$SLACK_APP_TOKEN" ]; then
+    _saveaccountconf_mutable SLACK_APP_TOKEN "$SLACK_APP_TOKEN"
+  fi
+
+  _content="$(printf "*%s*\n%s" "$_subject" "$_content" | _json_encode)"
+  _data="{\"text\": \"$_content\", "
+  if [ -n "$SLACK_APP_CHANNEL" ]; then
+    _data="$_data\"channel\": \"$SLACK_APP_CHANNEL\", "
+  fi
+  _data="$_data\"mrkdwn\": \"true\"}"
+
+  export _H1="Authorization: Bearer $SLACK_APP_TOKEN"
+
+  SLACK_APP_API_URL="https://slack.com/api/chat.postMessage"
+  if _post "$_data" "$SLACK_APP_API_URL" "" "POST" "application/json; charset=utf-8"; then
+    # shellcheck disable=SC2154
+    SLACK_APP_RESULT_OK=$(echo "$response" | _egrep_o 'ok" *: *true')
+    if [ "$?" = "0" ] && [ "$SLACK_APP_RESULT_OK" ]; then
+      _info "slack send success."
+      return 0
+    fi
+  fi
+  _err "slack send error."
+  _err "$response"
+  return 1
+}