Purpose: The purpose of this study is to analyze the mediating effect of family relationship between personality traits and postpartum depression by using the Actor-Partner Interdependence Mediation Model (APIMeM).Methods: Participants were 197 married couples within one year of childbirth. The APIMeM using path analysis was used to determine direct and indirect effects of personality and family relationships on postpartum depression between wives and husbands in AMOS 22.0.Results: Data showed an actor effect suggesting that the higher the neuroticism level in wives, the higher the postpartum depression level. In husbands, data indicated an actor effect suggesting that the higher the neuroticism level in husbands, the higher the postpartum depression level; however, neither wives nor husbands showed a partner effect. Data showed an actor effect suggesting that the higher the family relationship level for both wives and husbands, the lower the postpartum depression level; however, neither wives nor husbands showed a partner effect. Data showed a mediating effect of neuroticism in wives on postpartum depression through the family relationship.Conclusion: The study results indicate that, to prevent postpartum depression, it is necessary to develop a nursing intervention program for couples that can improve the personalities and family relationship of couples.