Tomodachi Spring / Summer 2019


“Sea of Japan,” The One and Only Internationally Established Name

The name “Sea of Japan” is the only internationally established name for the sea area concerned. Japan strongly opposes unfounded arguments concerning the name “Sea of Japan,” and is calling for a better understanding of the issue and support for Japan’s position from the international community in order to maintain the sole use of the name, “Sea of Japan.”

A map of the world created in Germany in 1856

The Origins of the Name “Sea of Japan”

 It is likely that the name “Sea of Japan” derives from the geographical factor that this sea area is mainly separated from the Pacific Ocean by the Japanese archipelago, and the name later became generally accepted worldwide. There are many sea areas that have been named in a similar way, such as the Andaman Sea, separated from the Indian Ocean by the Andaman Islands, and the Gulf of California, separated from the Pacific Ocean by the California Peninsula.

Unfounded Arguments from the Republic of Korea

 Despite these origins, at the Sixth United Nations Conference on the Standardization of Geographical Names in 1992, the Republic of Korea (ROK) began to claim that the name of the sea be changed to “East Sea,” a name used only within the ROK. The ROK claimed that “the name ‘Sea of Japan’ became widespread as a result of Japanese colonial rule in the early twentieth century.” Before this, the ROK had never made any objections to the term, either during bilateral talks or at international fora.
 Japan has studied maps possessed by the U.S. Library of Congress, the British Library, the Bibliothèque Nationale de France, the Berlin State Library and other bodies and found that the name Sea of Japan was already used with overwhelming frequency (87% in the US, 86% in the UK, 95% in France, 91% in Germany) in early 19th century maps. A world map designed and published in Germany in 1856 which was recently highlighted in the press also refers to the name “Sea of Japan.” Japan during the Edo Period (1603–1867) had an isolationist policy, and was unable to exercise any influence to establish the name “Sea of Japan.” It is clear that the name is not connected with Japanese colonial rule in the early twentieth century.

Results of the Ministry of Foreign Affairs’ Survey of Historical Maps

General Worldwide Acceptance of the Name “Sea of Japan”

 Countries around the world, including the United States, the United Kingdom, France, and Germany, use the name Sea of Japan. For example, the United States government has repeatedly stated that it uses the name, both on its website and through press conferences given by senior officials. The United Nations recognized “Sea of Japan” as the standard geographical term in 2004, and UN policy states that the standard geographical term be used in official UN publications. Furthermore, the International Hydrographic Organization’s Limits of Oceans and Seas, which includes names for the world’s seas, uses the name “Japan Sea.”

Protecting Legitimacy of the Name “Sea of Japan”

 If all countries followed the ROK and started naming the seas to their east or west as “East Sea” or “West Sea,” countless similar names would spread around the world causing unnecessary confusion. Japan will continue to oppose any attempts to change the only historically and internationally established name for the “Sea of Japan” to “East Sea,” a name that is used only within the ROK.


For more information, see the Ministry of Foreign Affairs of Japan website:


“Sea of Japan” A globally established name