Several studies regarding the effects of academic achievement on mental health problems have been conducted in adolescents but not in elementary school students. Therefore, the aim of the current study was to examine the effects of school achievement on depression in Korean elementary school students. The participants were 1,048, 5th to 6th elementary students in Seoul, Korea. The Spearman correlations between school achievement and depression were -0.31 for boys and -0.37 for girls (p <0.001 for both). After controlling for grader, the family economic status and self-esteem, higher achiever group showed a significantly low risk for depression in boys and girls. This study suggests that the lower school achievement is associated with a depressive mood in Korean elementary students. Therefore, students with lower academic performance are a risk group for depression.