This cross-sectional correlational study examined the association between parents' sense of family belonging and parent-infant attachment. Data were collected from 422 mothers and 422 fathers using a survey form, the Maternal Attachment Scale, the Father-Infant Attachment Scale, and the Family Belonging Scale. The mean Maternal Attachment Scale score among mothers was 97.84 ± 7.78, and the mean total score on the Father-Infant Attachment Scale among fathers was 70.40 ± 11.30. Mean total scores on the Family Belonging Scale did not differ significantly between mothers and fathers. Family belonging was positively and significantly correlated with both maternal attachment and father-infant attachment. Moderation analysis indicated that father-infant attachment moderated the relationship between mothers' family belonging and maternal attachment. Overall, these findings suggest that both mothers' and fathers' sense of belonging is an important factor in parent-infant attachment.