Purpose: This study aimed to examine the effect of parental self-esteem on late school-aged children’s media device addiction by mediating marital conflict and children’s self-esteem. Methods: This study used data from the 11th (2018) Panel Study on Korean Children. The participants consisted of 1,082 family triads (fathers, mothers, and children). Data were collected using the Rosenberg Self-Esteem Scale, Marital Conflict Scale, and K-Internet Addiction Scale. The data were analyzed using structural equation modeling with SPSS/WIN 27.0 and Mplus 8.7. Results: The final model showed a good fit for the data. Children’s media device addiction was directly related to mothers’ self-esteem, mothers’ marital conflict, and children’s self-esteem. Fathers’ self-esteem had a significant indirect effect on children’s media device addiction by mediating both fathers’ and mothers’ marital conflict. In addition, mothers’ self-esteem had a significant indirect effect on children’s media device addiction by mediating mothers’ marital conflict. Conclusion: The findings indicates that self-esteem and marital conflict for both fathers and mothers have a significant effect on children’s media device addiction. It suggests that more attention might be given to fathers and mothers in developing interventions to prevent children’s media device addiction.