This study analyzed the error cases of Japanese transitives by Korean learners. As a result, different error patterns were found in the cases where a transitive should be used as passive voice and vice versa. The error cases are as follows: ① In the case where a transitive should be used as passive voice, error cases were found frequently in the order of ⑴ preferring Japanese intransitive expression ⑵ expressing no transitive-intransitive verb pairs as passive voice ⑶ expressing transitive-intransitive verb pairs as passive voice ⑷ expressing「-teoku」as passive voice ⑸ etc. On the other hand, ② in the case where passive voice should be used as a transitive, error cases were found frequently in the order of ⑴ expressing no transitive-intransitive verb pairs as transitives ⑵ overgeneralization ⑶ vocabulary confrontation ⑷ etc. In grammar as it is one of the most difficult parts to master passive voice, this study aims to reconsider passive voice from a grammar educational viewpoint by analyzing the error patterns of passive voice focused on intransitives.