Hamaguchi Osachi (浜口 雄幸 April 1,1870–August 26,1931) was a Japanese politician and the 27th Prime Minister of Japan from July 2,1929 to April 14,1931.

He was born in Kochi Prefecture. Having risen through the ranks of the Japanese finance ministry, he became the chairman of his party and eventually the prime minister. He tried without much success to stabilize the Japanese economy against the worldwide Great Depression, and also to bring the military under more civilian control, incurring the enmity of rightwingers. He was shot in a train station on November 14 1930 and the wounds, though they were not severe enough to keep him from winning the February 1931 election, impacted his health.