Mitsugu Onishi (?????, Onishi Mitsugu; born 7 October 1952) is a Japanese photographer.
Born in Tokyo, Onishi graduated from the Tokyo College of Photography in 1974, rejoining a year later as a teacher, and staying there in that capacity until 1994.
Onishi photographed everyday life and his native Tokyo; he later turned his attention to suburban housing projects.
Onishi won the 22nd Taiyo award in 1985, and the 18th Kimura Ihei Award in 1993.
In addition to the collections of his photographs, he has written books about photography and cameras.