The purpose of this study was to investigate factors predicting smartphone addiction among high school student in Y city. Data were collected by structured questionnaires from July 1 to July 20 2013, and data were analyzed using descriptive statistics, correlation and multiple regression with SPSS/Win 21.0 program. The mean score for smartphone addiction was 30.91. A multivariate approach showed that predictors explained 18.4% of variance in smartphone addiction. Significant predictors of smartphone addiction were gender(β=.23), school achievement(β=.12), school adjustment(β=-.15) and online game addiction(β=.20). The factors affecting highly effective intervention techniques need to be applied to the development of programs to prevent smartphone addiction among high school student.