The main purpose of this study is to check whether the family relationship of adolescents has an impact on smartphone addiction and to verify of direct effects and moderating effects in according to self- efficacy. The survey was conducted to the adolescents who were second grade middle school students with 318 subjects in G metropolitan city. This study results found the followings: Family relationship and selfe-efficacy revealed direct influence on smartphone addiction. Moreover, the self-efficacy check the moderating effect of do family relationship on smartphone addiction. The results of this study are significant in that they demonstrated the influence of family relationship and self-effect on smartphone addiction and imply that self-efficacy can decrease or prevent smartphone addiction from family relationship problem.