diff --git a/README.md b/README.md
index a730f31..6287e88 100644
--- a/README.md
+++ b/README.md
@@ -18,8 +18,8 @@ Please read https://github.com/shiguredo/oss before use.
 Apache License 2.0
 
 ```
-Copyright 2020-2021, HARUYAMA Seigo (Original Author)
-Copyright 2020-2021, Shiguredo Inc.
+Copyright 2020-2023, HARUYAMA Seigo (Original Author)
+Copyright 2020-2023, Shiguredo Inc.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.