Objective: The purpose of this study was to investigate the relationships between young children s temperament, emotional regulation ability and mother s parenting sense of competence. Methods: The participants were comprised of 315 young children who attend a kindergarten or day care center and their mothers from Seoul, Inchon, and Gyeonggi-do Province. They completed questionnaires on temperament, emotion regulation ability, and parenting sense of competence. The data were analyzed by frequency analysis, Cronbach s ⍺, Pearson s correlation coefficients, and multiple regression analysis. Results: It was observed that young children s regularity/adaptability was positively correlated with sense of competence as a parent and young children s emotional regulation. Young children s regularity/adaptability was negatively correlated with dissatisfaction as a parent and young children s emotional instability/negativity. Sense of competence as a parent was positively correlated with young children s emotional regulation and negatively correlated with young children s emotional instability/negativity. In addition, it was further found that the mother’s parenting sense of competence tended to play a perfectly/partially mediating role between young children s temperament and young children s emotional regulation ability respectively. Conclusion/Implications: These results clearly indicated that parenting sense of competence plays a crucial role between young children s temperament and emotional regulation.