This paper analyzed finance system that was changed and evolved in colony period. Especially, this paper tried to explain colonial features of commercial banks with Chosun Commercial Bank analyzing. The study`s result is three points. First, the institutional base of commercial banks which was established newly in 1910s was greatly changed after 1920s. In other words, Chosun Commercial Bank became national bank through merger and acquisition between commercial banks that was established local banks before. Second, ownership and governance structure of Chosun Commercial Bank which allowed Japanese to become stockholder in 1917 was changed since late 1910s. And Chosun Commercial Bank which fund resource was limited was depended on loans of Chosun Bank as central bank. As a result, dependent relation of Chosun Commercial Bank on Chosun Bank was becoming. Third, Chosun Commercial Bank used the fund on commercial finance and to enforce governance base by early 1920s. But Chosun Commercial Bank used the fund to help wartime economy since Sino-Japan war evoked in 1937.