President Kennedy will name Edwin O. Reischauer, professor of Japanese History, as the United States Ambassador to Japan, the UPI reported yesterday.

According to the UPI, reliable sources in the Administration have confirmed that the President has already asked for Japanese approval of the appointment. Reischauer, the director of the Harvard-Yenching institute and an expert on Far Eastern affairs, recently returned from a tour of Japan and China.

Reischauer was in Washington last week for lengthy conferences with both Chester A. Bowles and Senator William J. Fulbright. Bowles, Under-secretary of State, has been active in the Administration's appointments to diplomatic posts, and Fulbright, chairman of the Senate Foreign Relations Committee, has repeatedly urged Reischauer's appointment.

Although Reischauer says that he went to Washington primarily to discuss the Korean situation with Administration officials, he confirmed yesterday that he and Bowles had also talked about other matters. Among them was the question of the Japanese ambassadorship.

When reached for comment, Reischauer said that he had received no official notification of any appointment. He did say, however, that, if he got the job, he "would very probably go to Japan."