In this research, the impact on adolescents' maladjustment at school that smart phone addiction has is
examined. And also the mediating effect of depression of smart phone addiction is also verified. For this
study, a survey was done ranging from middle school students to high school students. 394 students were
finally selected for the subject of analysis. This research model is verified through SPSS 23.0 for the
implementation and adaption of analysis of frequency, technology, interrelation and multiple regression
factors. Summaries of this research results are as follow. First, youths' smart phone addiction has
(meaningful) significant effect on maladjustment at school. Second, youths' smart phone addiction turned
out to have a (meaningful) significant effect on depression. Third, it's statistically proven that the deeper
depression gets, the higher maladjustment at school happens. Fourth, the mediating effect of depression of
youths' smart phone addiction in youths' maladjustment at school is verified. In conclusion, in terms of
social welfare practice, this research suggests taking action to intervention plan to prevent and cure for
youths' smart phone addiction. Furthermore, youths' smart phone addiction is the problem in school, home
and society as well as of students, so interventions of national policy supports are needed also.