diff --git a/README.md b/README.md
index 0fdf99f..ad7cf76 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,10 @@ These packages are automatically installed when installing with pip command.
 For extra information, please visit the [official documentation](https://py7zr.readthedocs.io/en/latest/user_guide.html#dependencies),
 especially the dependencies section.
 
+### ZIP
+
+We are using built-in library [`zipfile`](https://docs.python.org/3/library/zipfile.html). Please consider referring to the official documentation for more information.
+
 ## Config settings
 
 TODO