This study was intended to examine a potential mediation of rejection sensitivity between attachment to mother and peer conflict resolution strategies in late school-aged children and potential gender differences in these mediated relationships. Research participants were 454 5th or 6th graders in elementary schools in Seoul. The results are as follows: First, in rejection sensitivity, boys showed higher levels of rejection depression than girls. In the peer conflict resolution strategies, boys used the governance strategies more while girls using the compromise-cooperation strategies more. Second, child’s attachment to mother had significant positive correlations with the compromise-cooperation, avoidance, and yielding peer conflict resolution strategies. Third, rejection sensitivity mediated partly between attachment to mother and compromise-cooperation strategies. Fourth, partial mediation of rejection sensitivity was found both in boys and girls but the proportion of mediation was bigger in girls than boys. These results may contribute to better understanding of the factors affecting peer conflict resolution strategies in the school-aged children. Also, the results can provide useful tips for clinicians and teachers who want to intervene with children with peer relationships problems.