This study examined the mediating effect of self - efficacy on parent - child communication and peer relationship perceived by children. For this purpose, parent - child communication test, self - efficacy test, and peer relationship test were administered to 384 elementary school boys and girls in Busan and Kyungnam. The results of this study are as follows. First, there was a statistically significant correlation between perceived parent - child communication, peer relationship and self - efficacy. Second, there was a statistically significant difference in parent - child communication perceived by children, self - efficacy, parent - child communication, peer relationship, and self - efficacy on peer relationships. Third, self - efficacy partially mediated parent - child communication and peer relationship perceived by children. Based on the above results, the conclusions drawn from this study are as follows. It is found that parent - child communication perceived by children has a statistically significant effect on peer relations, so that self - efficacy is partly mediated between parent - child communication and peer relationship. Finally, the implications and limitations of this study were discussed.