The aim of this study is to look into the life of Ko, Myung-ja who was a woman activist in socialism during the Japanese colonial rule. Ko, Myung-ja got involved in Daegu Woman`s Youth Society in 1923, Joseon Woman`s Associate Society and Goryo Communist`s Youth Society in 1924; the next year, she was dispatched to Moscow Dongbangnoryeokja Communist College as an international student through the recommendation of the Goryo Communist Youth`s Society. She graduated from the Communist College in May, 1929 and participated in the Joseon Communist Party Reconstruction Movement after returning home in October of the same year. However, after being freed from the custody on charges of doing the Joseon Communist Party reconstruction movement, she finally renounced her socialist course, and instead, began to cooperate on imperial Japan`s integration policy between Korea and Japan & imperial Japan`s colonization policy. In other words, Go, Myung-ja transformed herself into a woman activist cooperating with imperial Japan from the socialist woman activist attempting to solve the issues of race, class and women. Nevertheless, her pro-Japanese background operated as obstacles to her activities after liberation from the Japanese colonial rule, and failed to share the political line with her revolutionary comrade, Park, Heon-young. Ko, Myung-ja organized the Labor People`s Party together with Yeo, Wun-hyeong in May, 1947 and worked as a member of the Central Executive Committee of the Labor People`s Party.