Kei Kumai (熊井 啓, Kumai Kei, 1 June 1930 – 23 May 2007) was a Japanese film director from Azumino, Nagano prefecture. After his studies in literature at Shinshu University, he began work as a director's assistant.

He won the Directors Guild of Japan New Directors Award for his first film, Nihon rettō, in 1965.[2] His 1972 film Shinobu Kawa was entered into the 8th Moscow International Film Festival.[3] His 1973 film Rise, Fair Sun was entered into the 24th Berlin International Film Festival.

Sandakan No. 8 received widespread acclaim for tackling the issue of a woman forced into prostitution in Borneo before the outbreak of World War II. The film was nominated for the Best Foreign Language Film at the 48th Academy Awards.