During the 36 years from 1910, the time Japan occupied South Korea to 15th, August, 1945, the recovery of South Korea, South Korea went through hardship and the dark ages of Japan' colonial control. In order to conquer Korea on thoughts and culture, Japan promoted Japanization of the South Korean Buddhism, so this period is also known as "the period of merging of religious groups under the rule of Japanese emperor." This paper tries to analyze the Japanization of Buddhism under the Japanese colonial rule in South Korea and its influence.