In this article, it was researched for mistranslation and misuse seen in common with Japanese writing and Korean translations of Korean Japanese learners. As a result, it was diversely found in passive expressions, postpositional particles, use of Chinese characters that is not found in Japanese, formal nouns "KOTO" "NO", intransitive verbs, transitive verbs, expressions of giving and receiving, "~TE" aspects, tense and "~TE KURU/~ Te IKU", word orders. There is a mutual dependency in ability between the languages. Skilful learners in writing of the second language are excellent in the translation ability to mother tongue. Writing ability and translation capabilities have something directly and indirectly in common, therefore, it is better to educate together and this can be said that it creates a synergy effect. Moreover, it must be considered a method of education not only the creation of appropriate composition and textbook for translation but also updating a database of typical misuse and mistranslation.