diff --git a/ppcls/utils/save_load.py b/ppcls/utils/save_load.py
index e68a7af416a9f45061dc53640aea9b1ee5b09089..302171767b0eb634dad2079b255d197553717bd3 100644
--- a/ppcls/utils/save_load.py
+++ b/ppcls/utils/save_load.py
@@ -42,7 +42,7 @@ def _mkdir_if_not_exist(path):
                     'be happy if some process has already created {}'.format(
                         path))
             else:
-                raise OSError('failed to mkdir {}'.format(path))
+                raise OSError('Failed to mkdir {}'.format(path))
 
 
 def _load_state(path):