The purpose of this study was to investigate the effects of mother's depression and sleep quality, and marital conflict on children's sleep problem. Subjects of this study consisted of 536 mothers having below 5-year-old children from 3 preschools and 9-year-old children from 4 schools in Cheongju city. Data were analyzed by SPSS 12.0 with the methods of frequency, percentage, Cronbach α coefficient, t-test, F-te st, Scheffé post-hoc test, correlation, and hierarchical regression. The result of this study implies that there was significant differences in children's sleep problem according to children's age and was an interacting effect between family's income and mother's depression, sleep quality, and marital conflict on children's sleep problem.