This study aims on examining whether Korean-Vietnamese dictionary which Vietnamese learners of learning Korean language mostly use has errors of Korean language. We will also analyze which kinds of errors are shown in Korean-Vietnamese dictionary and will research their frequencies. Of error types such as examining result of dictionary, vocabulary, grammar, others and mingling, other errors showed highest ratio as 52.6%, and of these other errors, spacing words error showed ratio of 44%. Second in ratio is shaping error of vocabulary among vocabulary errors and its ratio is 20.2%, which spelling errors are most occurred. Spacing words and spelling which are most basic rule in dictionary have frequent errors. This may provide wrong information to Korean learners and may cause confusion when learning. Learners mostly depend on dictionary about vocabulary. The dictionary for Korean language learners is still short in quantity, and in particular, dictionary for Vietnamese learners may be said to be none. The dictionary for Korean language learners as well as for Vietnamese learners should be published urgently, and usage of vocabulary and error examples with exact explanation should be provided. We think that this study will help to understand the errors of Vietnamese learners a little, and further more it will be a reference to search the plan using to vocabulary instruction or instruction and study on Vietnamese learners. (Daegu University)