The purpose of this study is to examine the double mediating effect of self-esteem and peer attachment in elementary school students in the effect of marital conflict on the happiness of elementary school students. For this purpose, a double-mediated analysis was conducted using PROCESS macro version 4.1 (Model 6) on the data of 1,392 elementary school children in grades 4-5 and their guardians who participated in the 11th year of the Panel Study on Korean Children. As a result of the analysis, first, marital conflict was significant as a negative correlation with peer attachment, self-esteem and happiness of elementary school students, and peer attachment and self-esteem were significant as a positive correlation with happiness. Second, in the relationship between marital conflict and happiness, self-esteem and peer attachment showed a sequential double mediating effect. It was found that, even if marital conflict is severe, children's peer attachment and self-esteem are very important variables.