Shinohara was born 1932 in the neighborhood of Kojimachi in central Tokyo. In 1952, he enrolled at the Department of Oil Painting at Tokyo University of the Arts to study under the renowned painter Takeshi Hayashi. However, Shinohara quit the university in 1957 short of graduation. In 1960, Shinohara together with Masanobu Yoshimura, Genpei Akasegawa, and Shusaku Arakawa (all of them former participants at the Yomiuri Independent Exhibition) established the art group “Neo Dada Organizers.”

His work during this era centered on what he called “Imitation Art,” and the “Oiran (Courtesan)” series. While his “Boxing Paintings” became his signature work series, this was initially not intended as art but as media performance, as he later explained to fellow Neo Dada member Akasegawa. In 1969, Shinohara was granted a Rockefeller Fellowship, allowing him to settle in New York. In 2007, he won the 48th Mainichi Art Prize.