The purpose of this study was to determine the effect of expenditure on private education and stress caused by private education on the parental efficacy of mothers of junior and senior high school students. The subjects were 300 mothers of students who were enrolled in the junior and senior high school in Seoul and its suburbs. The results were as follows: First, the level of stress from private education was found to be higher than the degree of parental efficacy. Second, a hierarchical regression analysis was performed by using expenditure on private education and stress caused by private education as independent variables and the socio-demographic characteristics of mothers as control variables in order to identify their effect on the parental efficacy of mothers of junior and senior high school students. The results show that stress from private education and monthly income were significantly related to parental efficacy. That is, the lower the level of stress from private education and the higher the monthly income, the higher was the degree of parental efficacy. These findings suggest that expenditure on private education seems to be determined by the household income level; thus, income may affect psychological stress and parental efficacy of mothers with respect to the process of providing private education.