The purpose of this study is to investigate depression degree of school children and its influence factors, and to provide basic data for their mental health promotion, prevention of depression and intervention. For the research subject, this study targeted 487 school children in the 4th, 5th and 6th degrees at 2 elementary schools in Busan Metropolitan City, Korea, from November 1 to 10, 2011. For the research tool, it used depression, self-esteem, academic stress, relationship with teacher, relationship with friends, satisfaction of family and body image scale. For the method of data analysis, SPSS WIN 19.0 statistical program was used; average, percentage, independent sample t-test, ANOVA, and Pearson's Correlation Coefficient were analyzed; the influence factors of depression were verified by the multiple regression analysis. Depression degrees of the research subjects were found: that of the severe depression group was 13.1%; minor depression group 18.7%; normal range group 68.2%. As a result, a factor having the greatest influence on the subjects’ depression degree was self-esteem(β=-.34, p<.001), followed by academic stress(β=.30, p<.001), body image(β=-.15, p<.001), relationship with friends(β=-.09, p=.023), and satisfaction of family(β=-.09, p=.041). These factors showed 54% explanation power of depression. Therefore, through self-esteem improvement programs, management of academic stress, the support for the positive body image, small group activities for close friendships and parental education, efforts should be made to prevent and intervene school children’s depression.