Objective: The aim of this study is to investigate children’s smart-phone overdependence and to analyzes the effect of children’s self-regulation ability and smart-phone use variables on their smart-phone overdependence. Methods: Total 360 fifth ad sixth graders in elementary schools in Gwangju and Jellanam-do participated in this study. They answered the ques- tionnaire about their smart-phone usage and self-controal ability. Results: First, Smartphone overdependence scores tended to be low with an average score of 2.0. It was also found that more than half of the students have been using smartphones since infancy and the lower grades of elementary school. Children's smartphone usage time showed a similar response rate of 15-20% in all time zone response categories from more than 1 hour to more than 5 hours. Second, the variable that had the greatest influence on smart-phone overdependence was children's self-regulation ability. Also, the variables affecting each sub-factor of smart-phone overdependence were different. Conc lus i ons: This study suggestes some practical advice to prevent and reduce children’s smart-phone overdependence.