Masushi Ōuchi

was a Japanese weightlifter who won a bronze medal at the 1964 Summer Olympics and a silver medal at the 1968 Summer Olympics. He won two gold medals at the Asian Games in 1966 and 1970. He further became the world champion in the light-heavyweight category in 1969. In 1965–1969 Ouchi set eight world records – six in the snatch and two in the total. Later in life, Ouchi won four world titles in the masters category.

Ouchi was born in Kōriyama, Fukushima, Japan, on September 28, 1943. He took weightlifting as a student at Hosei University and an employee for the Tokyo Metropolitan Police Department. He died on June 6, 2011, at the age of 67.