Blue Flag is a certification for marine environments. As of March 2022, it has been granted to 4,831 beaches, marinas, and boating tour operators from 50 countries. While beaches in Korea and India have been awarded the Blue Flag, Japan was the first in Asia to have Blue Flag-certified beaches and marinas. In this article, I would like to introduce the history, criteria, and characteristics of the Blue Flag certification that was founded in France over 37 years ago.