Objectives: The main purpose of this study was to examine factors associated with depression of middle school students in relation to self-esteem, type A behavior pattern, and locus of control. Methods: A survey was administered to a convenience sample of 309 middle school students. The data analysis procedure included frequency distribution, t-test, ANOVA, Pearson correlation coefficients, and stepwise multiple regression using depression as the dependent variable. Results: The prevalence of depression was 27.2%. Stepwise multiple regression revealed that the factors such as self-esteem(${eta}$=0.422, p<0.001), type A behavior pattern(${eta}$=0.166, p<0.001), and locus of control(${eta}$=-0.165, p<0.001) turned out to be significant affecting factors. Forty nine percent of variance in depression was explained by these factors(40% of variance by self-esteem). Conclusions: The findings suggest that personal internalizing variables should be considered when developing mental health education program to prevent the occurrence of depression for middle school students.