The purpose of this study is to confirm the use of smartphones by children aged 3 to 5 years old and to propose a plan for prevention of overdependence. To this end, the data of 909 people aged 3 to 5 years old were used in the study from the raw data of the '2019 Smartphone Overdependence Survey' conducted by the National Information Society Agency. The research results are as follows : Infants aged 3 to 5 were using their smartphone for an average of more than an hour a day, it was found that smartphones were used in the order of video services and games, listening to music, educational contents and search services. Parents were found to be tolerant of their children's smartphone usage time and dependence. In particular, despite the fact that most infants and toddlers use smartphones to watch videos and use game content, they are not concerned. Therefore, parental education content for the use of smartphones by infants and toddlers needs to include comprehensive content on media use.