The purpose of this study was to examine the relationships between parents’ affectionate parenting behavior, preschooler’s effortful control, and conscience. In this study, the subjects consisted of 335 preschoolers (Mmonth=65.86) and their parents. The major results of this study were as follows. First, there were positive correlations between parents’ affectionate parenting behavior, preschooler’s effortful control, and conscience. Second, preschooler’s effortful control mediated the effects of affectionate parenting behavior upon preschooler’s conscience. Third, preschooler’s effortful control(Time 1) had effects upon conscience(Time 2). In conclusion, this study revealed that parents’ affectionate parenting behavior and preschooler’s effortful control can have a significant impact on the level of preschooler’s conscience.