Purpose: Postpartum depression is a well-known risk factor, and postpartum anxiety and parity are potential risk factors, for mother-infant bonding disorder. However, few studies have focused on the relationships among these factors and mother-infant bonding. This cross-sectional study explored the associations between depression, anxiety and parity, and mother-infant bonding. Materials and Methods: Japanese mothers, both primiparas and multiparas, completed the Mother-to-Infant Bonding Scale (MIBS) and the Hospital Anxiety and Depression Scale (HADS) one month after childbirth. We performed a stepwise multiple regression analysis with the forward selection method to assess the effects of HADS anxiety and depression scores and parity as independent variables on mother-infant bonding as the dependent variable. Results: A total of 2379 Japanese mothers (1116 primiparas and 1263 multiparas) took part in the study. MIBS score (2.89 ± 2.68 vs 1.60 ± 2.11; p < 0.0001) was significantly higher in primiparas than in multiparas. HADS anxiety (6.55 ± 4.06 vs 4.63 ± 3.41; p < 0.0001) and depression (6.56 ± 3.43 vs 5.98 ± 3.20; p < 0.0001) scores were also significantly higher in primiparas than in multiparas. A stepwise multiple regression analysis with the forward selection method revealed that HADS depression and anxiety scores and parity were significantly associated with MIBS score (p = 0.003, 0.015 and 0.023). Conclusion: Depression, anxiety and primiparity were negatively associated with mother-infant bonding one month after childbirth.