Kang Mun-sok (1906–1955) was a Korean socialist activist during the Japanese occupation period and thereafter.
Born in Namjeju County on Jeju Province, he became active in the socialist movement in Japan starting in the 1920s.
After the end of World War II, in September 1945 he joined Pak's reconstructed Communist Party of Korea, serving as Pak's right hand as head of the publicity department while also working as a cadre of the Communist Party of South Korea.
After the Workers Party of South Korea was outlawed by American military government of Korea, Kang moved to North Korea, but is believed to have been killed when the members of the WPSK were purged due to the Pak-Yi espionage affair.
He was denounced for individualism and regionalism by Kim Il Sung at a party congress in 1955.