There has been a huge amount of research on errors of language learners. However, most of them have focused on syntactic errors and those about lexical errors are not found easily despite the importance of lexical learning for the language learners. The case is even rarer for Korean language. In line with this background, this study was designed to find out what the actual features of lexical errors made by some American college learners of Korean language. These beginner-intermediate level learners showed a variety of features of lexical errors. Detailed explanations and discussion on the finding are followed. It concludes with some implications and some suggestions for the future research.