Objective: This study examined the effects of mothers’reactions to children’s negative emotions on the children’s social power through children’s emotional regulation ability. Methods: A total of 339 four-year and five- year old preschoolers, and their mother and teachers in Seoul and Gyeongi participated in the study. Data were analyzed by path analysis using AMOS 21.0 program. Results: The results were as follows: First, mothers’reactions to children’s negative emotions were significantly related to children’s emotional regulation ability and social power. Also, children’s emotional regulation ability was significantly associated with children’s social power. Second, mothers’reactions to children’s negative emotions had indirect effects on social power – prosocial leadership and social dominance-through children’s emotional regulation ability. Conclusion/Implications: The results of this study revealed the mediating role of children’s emotional regulation ability between mothers’reactions to children’s negative emotions and children’s social power. Also, these findings will be helpful in order to understand children’s social power and to develop parent education programs.