Mokichi Saitō (斎藤 茂吉 Saitō Mokichi, May 14, 1882 - February 25, 1953) was a Japanese poet of the Taishō period, a member of Araragi school, and a psychiatrist.
The psychiatrist Shigeta Saitō is his first son, the novelist Morio Kita is his second son and the essayist Yuka Saitō is his granddaughter.
Saitō was born in a village now part of Kaminoyama, Yamagata. He studied under Itō Sachio, a writer initiating magazines such as Araragi. By the time of his death, Saitō had written seventeen collections of poems and 17,907 poems. He received the Order of Culture in 1951.
He was the family doctor of author Ryūnosuke Akutagawa and assisted in his suicide.