After Japanese schools were established in Korea in 1891, Japanese language was adopted in school education. This article aims to study on how teachers try to teach Japanese according to their own objectives in the 1891s-1920s. After the Russian-Japanese war, the educational objectives changed from civilization and practical use to assimilation. This happened through the change of language of instruction from Korean to Japanese language. This study focuses on the Japanese language teaching method from the teachers' point of view. Additionally, this study also aims to clarify what kind of assertions were discussed in the then Korean and Japanese educational journals.