Mun Chang-bom was the Minister of Transportation in the Provisional Government in Shanghai but eventually resigned. On September 15, 1920, he declared support of the communists.
Mun was one of the leaders of the Korean National Council and his declaration of support held great weight among the Koreans.
He was the chairman of the Chita Hanjok Kongsan-tang Uijong-hoe (Chita Korean Communist Party Council), along with Kim Chol-hun and other members of the Irkutsk communist group
In June 1921, Man Chang-bom and the Irkutsk group form the Koryo Hyongmyong Gunjong Uihoe (Korean Revolutionary Military Government Council; KRMGC) to detach forces from the Korean Volunteer Army