Objective As smartphone use is becoming more common, the age of initial exposure to devices is becoming younger. Young children’s screen use is influenced by various factors; it is more directly dependent on family environment than school-aged children. Our study aimed to examine the effect of mother’s smartphone addition on their child’s smartphone use. Methods Participants were from the Kids Cohort for Understanding of internet addiction Risk factors in early childhood (K-CURE) study. Adult smartphone addiction self-diagnosis scale was used to evaluate smartphone addiction degree of mother. Child’s smartphone use was assessed by parental questionnaire. Using logistic regression analysis, we examine the association between mother’s smartphone addiction and child’s smartphone use. Results After adjusting for other factors, mother’s smartphone addiction is related with early smartphone exposure of children. Highrisk group’s children was exposed to smartphone earlier than low risk group (adjusted OR, 0.418; p=0.021). Contrary to expectation, there is no correlation between mother’s smartphone addiction and child’s smartphone use time. Conclusion Our study explain that mother’s smartphone addiction can affect early smartphone exposure on children. Based on our findings, further study might explore the effect of early smartphone exposure on children.