Shōzō Shimamoto (嶋本 昭三, Shimamoto Shōzō, January 22, 1928 – January 25, 2013) was a Japanese artist. Having studied with Jirō Yoshihara, the future Gutai leader, from 1947, Shimamoto was a key founding member of Gutai along with Yoshihara and fifteen others in August, 1954. He was close to the leader Yoshihara and actively engaged in the early activities and group administrations. He worked with a wide variety of techniques, such as poking holes in layered newspaper, throwing bottles of paint at canvases, experimenting with film and stage performances, and composing sound art. He was particularly noted for his innovative performance art. Indeed, when Yoshihara turned to focus more on painting, upon his meeting with the French art critic Michel Tapié, Shimamoto continued to urge the leader to pursue this direction, wanting to work with Allan Kaprow, for example.
After Gutai, he became known for his mail art activities with the group AU and the continuation of his painting performances which he staged around the world. He died of acute heart failure in Nishinomiya City, Hyōgo prefecture.