diff --git a/plugin-development/api-config-types.md b/plugin-development/api-config-types.md
index 18106293..a6e0007a 100644
--- a/plugin-development/api-config-types.md
+++ b/plugin-development/api-config-types.md
@@ -10,6 +10,8 @@
 
   the parameter is not configured.
 
+  **NOTE**: It doesn't perform type conversion such as `time` type, and the specified default value is used as is.
+
 ```ruby
 # Required parameter: The configuration must have this parameter like 'param1 10'.
 config_param :param1, :integer