The purpose of this study was to understand path of internal narcissism toward SNS addiction tendency of middle school students. The study intended to test the hypothesis that internal narcissism personality would lead to the SNS addiction tendency through interpersonal problems and that the internal narcissism effect on the interpersonal problems can depend on Gender difference The subjects of the study were 240 middle school students (95 male and 145 female students) in Gwangju area. The descriptive statistics, correlation analysis, and SPSS Macro PROCESS Model were used. The results of the study are as follows. First, there was a significant positive interpersonal problems mediation efffect between inner narcissism and SNS addiction tendency of middle school students. Second, as a result of examining Gender difference moderatiing effect between internal narcissism, and interpersonal problems relationship. according to gender difference statistically significant. Third, Moderated mediation effect of gender difference and interpersonal problems between internal narcissism personality and SNS addiction tendency relationship is statistically significant. Recently, social networking has become a serious problem in our society and it shows the highest rate of addiction in early middle school students. The purpose of this study was to investigate the effects of psychological factors of inner narcissism and interpersonal problems on the SNS addiction tendency, focusing on the gender differences in middle school students, and to provide basic data to prevent adolescent SNS addiction problems have.