The focus of this paper will be to investigate the properties of the Korean reflexive pronouns {caki, sasin} and to analyze the errors made using these reflexive pronouns through the corpus of Korean learners. These two words {caki} and {sasin} are the traditional reflexive pronouns and are different from the Chinese words {自己}. The typical properties are like this. First, in general there are no differences in terms of usage between these two words {caki, sasin}. Second, only {sasin} can be used when wanting to emphasizing the usage. Third, in the reflexive usage, {caki} has many constraints. For example, one constraint that {caki} has is that you cannot use it when referring to first and second person. In contrast, {sasin} has no constraints. Also {sasin} can be used as the antecedent (honorable person) and in terms of frequency is also used more often than {caki}. However Korean learners use {caki} more than{sasin} because of the Chinese word {自己} as well as overgeneralization.