Nobuhiko Ushiba, 75, a Japanese career diplomat who served as his country's ambassador to the United States and chief negotiator for international trade, died here Dec. 31 of a liver ailment.

Mr. Ushiba's term as ambassador from 1970 to 1973 is remembered as a tumultuous time in the two countries' relations, due to the two "Nixon shocks" -- detente with China and the devaluation of the dollar.

Later in his career, Mr. Ushiba emerged as a sort of statesman of international trade, serving on various "wisemen's" commissions and signing a comprehensive trade agreement with the U.S. in 1978.

Mr. Ushiba was born in Kobe. He attended the elite Tokyo Imperial University and entered the diplomatic service in 1932. During World War II, he served as a junior officer in the Japanese embassy in Berlin.

In 1951, he became director general of the International Trade Bureau of the Ministry of International Trade and Industry, the powerful government agency which has overseen much of Japan's rapid economic growth.

In the late 1960s, after serving in Burma and Canada, Mr. Ushiba was appointed vice minister of foreign affairs, the Foreign Ministry's highest position for a career official.

After returning from Washington in 1973, he served as an adviser to the Foreign Ministry and minister of state for external economic affairs, a cabinet post that was created especially for him.

As minister, he signed a major trade agreement in Tokyo with U.S. trade representative Robert Straus. Between 1978 and 1979, he headed the Japanese delegation to the "Tokyo Round" of multilateral trade negotiations.

From 1979 to 1981, he was Japanese chairman of the Japan-U.S. Economic Relations Group, a joint study commission set up by the two countries. From 1983 until this year, he held the same post on a similar body, the Japan-U.S. Advisory Commission.

Survivors include his wife, Fujiko, and four children.