Objectives: This study tested the mediating effects of mothers' postnatal depression, mother-to-infant bonding failure, and hostile attributions to children's behaviors at 1 month postnatal on the relationship between intimate partner violence (IPV) during pregnancy and maternal child abuse at 3 months postnatal. Method: Pregnant women in the third trimester of pregnancy who visited 1 of 2 antenatal clinics in Tokyo, Japan, were recruited, and asked to complete questionnaires during their pregnancy, and at 1 month and 3 months postnatal, from June 2016 to September 2017. IPV during pregnancy, postnatal depression, mother-to-infant bonding failure, hostile attributions to children's behaviors, and maternal child abuse were evaluated using the Violence Against Women Screen, the Edinburgh Postnatal Depression Scale, the Mother-to-Infant Bonding Scale, the Scale of Mother's Recognition on Child's Behaviors, and ad hoc questions, respectively. Results: The data from 442 participants were used for analyses. The main finding of this study was that hostile attributions to children's behaviors 1 month after birth have a mediating effect on the relationship between IPV during the pregnancy and maternal child abuse 3 months after birth (indirect effect ϭ .06, p ϭ .03). The effects of mother-to-infant bonding failure and postnatal depression were not significant. Conclusions: This study suggests that health interventions focused on assessing and reducing hostile attributions to children's behaviors could prevent maternal child abuse in the postnatal period among abused pregnant women.