The purpose of present study is to investigate what is the most important factor among personality, social relation perception, and cultural influence on North Korean Defectors' self-enhancement bias, and how their self-enhancement bias influences on their psychological adaptation in South Korea. To implement this, we compared the self-enhancement bias of South Korean undergraduates and North Korean Defector undergraduates, and social desirability, too. However, there was no significant result. Based on this outcome, we focused on 121 North Korean Defectors' self-enhancement bias mechanism. We found that personality and social relation perception factors influenced significantly on their self- enhancement bias and furthermore their self-enhancement bias affected on their psychological adaptation. In addition to this, we identified sex difference at this mechanism. That is, women showed the same pattern with the existing findings in the study of self-enhancement bias mechanism, but men showed somewhat different pattern.