Zenko Suzuki, 93, the Japanese prime minister from 1980 to 1982, died July 19 at a hospital in Tokyo, a hospital official said.
The Kyodo News agency, citing family members, said he died of pneumonia.
Mr. Suzuki was appointed prime minister in July 1980 after the sudden death of his predecessor, Masayoshi Ohira.
A member of Japan's long-ruling Liberal Democratic Party, Mr. Suzuki took over during a period marked by instability as cabinets frequently changed and factional politics splintered parties.
His strong mediation skills had helped him chair the party's executive council 10 times and win support early in his term.
In foreign policy, Mr. Suzuki helped define the close post-World War II relationship between Japan and the United States as an "alliance" after a summit with President Ronald Reagan in 1981.
However, he was also known for his blunders, including his handling of allegations immediately before a scheduled trip to Beijing in 1982 that education ministry officials were trying to gloss over Japan's wartime aggression in China in its official textbooks.
Mr. Suzuki also began to draw criticism that he lacked the leadership to push through his pledges on fiscal reform.
Amid the escalating textbook scandal and deteriorating relations with Washington, Mr. Suzuki resigned in 1982.
He was succeeded by Yasuhiro Nakasone, one of Japan's longest-serving prime ministers.