The present study examined the relation between self-regulation (self-assertion and self-inhibition) and problem behavior (antisocial and asocial behavior) in preschool children. 332 children were rated by their teachers about self-regulation and problem behavior. The results of analysis of variance showed the followings: (1) Children with low self-inhibition showed higher antisocial behavior score than children with high self-inhibition regardless of gender or age. (2) Children with high self-assertion showed higher antisocial behavior score than children with low self-assertion regarding the 3- and 4-year old girls. (3) Children with low self-assertion showed higher asocial behavior score than children with high self-assertion regarding the 3- and 5-year old boys and the 5-year old girls. (4) Children with low self-assertion showed higher antisocial behavior score than children with high self-assertion, and children with low self-inhibition showed higher asocial behavior score than children with high self-inhibition concerning the 5-year old boys. These results were discussed in view of gender and developmental differences.