The purpose of this study was to determine the effect of smartphone use on the social personal development of children in school at Al-Marhamah Kindergarten. This study used quantitative methods with cross sectional design. The population in this study were all parents of students and Al-Marhamah kindergarten students in Majalengka Regency with total sample of 33 mothers and 33 children. Tthe sampling technique used was simple random sampling. The analysis used univariate by using frequency distribution and bivariate by using Chi Square test with α = (0, 05). The results showed that there was an influence between the use of mobile phones and social personal development of pre-school age children with the probability value p 0.017