Introduction: Postpartum Depression (PPD) is one of the major health problems that have adverse effects on mother and family and can be related to many factors. It is one of the most common psychiatric disorders and a common problem of human life. Aim: To determine the predisposing factors of PPD. Materials and Methods: This was a descriptive-analytical and cross-sectional study in which 242 women referred to Kermanshah health centres (two months after delivery), were selected by cluster random sampling. Data were collected using a standard Edinburgh Depression Inventory. Data were analysed by SPSS software using chi-square, t-test and ANOVA. Results: The average age of study participants was 29 years. A total of 11.3% of mothers had moderate depression and 44.8% had severe depression. There was a statistically significant relationship between the level of depression with spouse support, maternal support, desire and unwanted pregnancy (p-value <0.05). On the other hand, there was no significant relationship between level of depression and type of delivery; mother's education and gender of infant (p-value >0.05). The prevalence of depression was also higher in those with unwanted pregnancy (p-value <0.05). Conclusion: More than half of the study population had severe depression. Spouse support in reducing PPD can be effective. So, it is necessary to educate the spouses about the important issue of PPD. [ABSTRACT FROM AUTHOR]