Objective: This study examined the structural relationship between interaction of children’s peer play, teacher-child interaction and children’s social skill and aimed to learn the mediating effect of teacher-child interaction in relationship between interaction of children’s peer play and their social skill. Methods: Materials of the 7th year Korean Children’s Panel (2014) of Korea Institute of Child Care and Education were used in the study. The subjects included 1,203 children who participated in the 7th year survey and their homeroom teachers. Collected data underwent descriptive statistical analysis, correlation analysis, confirmatory factor analysis, analysis of structural model, and path analysis using SPSS 23.0 and AMOS 22.0. Results: The study showed the following results: (1) interaction of children’s peer play had a positive effect on their social skill; (2) interaction of children’s peer play had a positive effect on teacher-child interaction; (3) teacher-child interaction had a positive effect on children’s social skill; and (4) teacher-child interaction partly mediated in the effect of interaction of children’s peer play on their social skill. Conclusions: The study suggested the importance of teacher-child interaction in the relationship between interaction of children’s peer play and their social skills. Therefore, the authors proposed teacher education to improve the quality of teacher-child interaction.