This study examined the relationships between mother's psychological control and child's behavior problems (hyperactivity, aggression, anxiety, social withdrawal, and social immaturity). The participants were mothers of 207 preschoolers residing in Kyonggido. Mothers were asked to complete questionnaires measuring their psychological control over their child and their child's levels of behavior problems. Maternal psychological control was assessed using the Psychological Control Scale(Barber, 1996) and the five child problem dimensions were assessed using the CBCL. The data were analyzed using ANOVA's and hierarchial multiple regression analyses. The study found that mother's psychological control significantly related to the levels of child's hyperactivity, aggression, anxiety, social withdrawal, and social immaturity. Mother's psychological control particularly strongly affected levels of child's hyperactivity and aggression. Given the results of this study, it was concluded that mother's control over her child through psychological controlling methods appears to have negative impacts on child's behaviors and psychosocial adjustment.