The purpose of this study is to select a synonym list and to discuss methods of describing synonyms for Korean learners. For selection of the synonym list, we will use lerner error corpus. Also we will select the list that abstracts errors of lexical replacement in same parts of speech from types of lexical errors, and compare the list with some lists of preceding studies and dictionaries. What is more, we will classify the list into two types according to cause of the creation of each error. The first type is semantical similarities. The second type is differences of registers.