Shinji Sōmai (相米 慎二, Sōmai Shinji, 13 January 1948 – 9 September 2001) was a Japanese film director. He was born in Morioka, Iwate Prefecture, and was brought up in Hokkaido. Somai began his career in 1975 as an assistant director with Nikkatsu Co., one of Japan's leading film production companies, after he dropped out of Chuo University.

Somai made made his debut as a director in 1980 with The Terrible Couple - an adaptation of a popular boys' manga of the time. The film deals with the trials and tribulations of adolescence, presaging a long thread of Somai works in which young people are called upon to test their capabilities while discovering the unreliable nature of adult society. In Somai's hands, children and teenagers are always treated and presented sympathetically and seriously.

An actor's director from the start, Somai's trademark was a use of long takes, usually involving constantly-moving and spectacularly sweeping shots, which he felt allowed his cast to achieve the proper mood for scenes which would have been ruined by excessively quick editing. Perhaps the most extraordinary use of this technique is to be found in his 1985 film Lost Chapter of Snow: Passion (one of three of his films released that year), in which Somai uses an apparently single fourteen-minute take to reveal a succession of significant events in one character's childhood.

The best of Somai's films often straddle genres, taking off in unpredictable directions toward stimulating destinations.

Somai directed 13 films between 1980 and 2000. He died of lung cancer at 53.