Purpose: The purpose of this study was to investigate the effect of stress, social support and self-efficacy on the mental health of female undergraduate students. Method: Three hundred ninety-nine undergraduate students were conveniently selected from a university in Seoul. The instruments used in this study were stress, social support, self-efficacy, and mental health scales. ANOVA, t-test, Pearson correlation coefficients, and stepwise multiple regression with SPSS Win 16.0 Version were used to analyze the data. Results: Mental health was significantly influenced by stress, social support, self-efficacy, and monthly expenditures. These variables accounted for 44.2% of the variance in mental health. Conclusion: The important factor that was found to affect the mental health of undergraduate female students was stress. Therefore, future studies need to be pursued to develop various strategies, such as stress relief programs, for mental health promotion of female undergraduate students.