Purpose:The aim of this research is to examine the moderating effects of self-esteem and resilience in the relationship between smartphone addiction and depression among middle school students. Methods: Data were collected from 324 middle school students in D City during the period of July 1st-17th, 2015. Multiple regression analysis, the Baron & Kenny's mediation verification, and Sobel test were conducted to measure the mediating effects of self-esteem and resilience on depression. Results: There were significant correlations among the variables; smartphone addiction, self-esteem, resilience, and depression. Self-esteem had a complete mediating effect (β=-.40, p<.001) in the relationship between smartphone addiction and depression (Sobel test: Z=4.68, p<.001). Resilience had a partial mediating effect (β=-.15, p<.001) in the relationship between smartphone addiction and depression (Sobel test: Z=2.40, p<.001). Conclusion: This study suggests to apply self-esteem and resilience in developing nursing intervention programs for adolescent depression caused by smartphone addiction.