Foreign Minister Fumio Kishida says it is "unacceptable" that the official website for the 2018 Pyeongchang Olympics refers to disputed Sea of Japan isles under the South Korean name of "Dokdo."
"It goes against the Olympic Charter, which calls for mutual understanding and opposes the political use of sports," Kishida told reporters Friday.
Japan claims the South Korean-controlled pair of islets and calls them Takeshima.
Japan has requested South Korea to address the issue, he added.
The Japan Olympic Committee has also asked the International Olympic Committee and the Korean Olympic Committee to correct the name, a source close to the matter said Friday.
The website introduces the islets by saying in English, "Dokdo holds a special place in the hearts of Koreans as they hold pride in defending Korea's easternmost reached territory."
It also refers to the waters that Japan calls the Sea of Japan under the South Korean name of "East Sea."
"It is unacceptable in light of our country's stance over the sovereignty of Takeshima and over the naming of the Sea of Japan," Kishida said.