Colonial rule of Korea by Japanese imperialism was one of the main factors regulating Korean modern history. It provided a cause of division of Korea as well as had a profound effect on formation of system of South and North Korea. Spread of human heritage represented by the pro-Japanese group and material heritage and institutional heritage and ideological heritage and cultural heritage and so on reveals that remnants of colonial rule by Japanese imperialism are still alive widely in our society. Our Japanese terminologies and styles used unwittingly until today is a good indication showing that those remnants have a strong life. After liberation, ways of countermeasure by South and North Korea against remnants of Japanese imperialism presented a striking contrast. Unlike South Korea taking a negative attitude for liquidating them, North Korea did not allow even remnants remaining in notions and habits of individuals. That North Korea spent one year to establish legal concept and categories of the pro-Japanese group reveals difficulty of liquidation task of heritages of Japanese imperialism. To set a concrete standard for the pro-Japanese acts and the pro-Japanese group was a task hard to resolve. Researches examining liquidation ways of the pro-Japanese group and heritages of Japanese imperialism by North Korea are worthy in that they can provide a meaningful reference South Korea that did not yet complete the task. This study examining liquidation process of heritages of Japanese imperialism by North Korea from liberation to outbreak of Korean war noted liquidation of human heritage that is to say the pro-Japanese group as well as liquidation of material,institutional, ideological, cultural heritages.