Background and Aim: Postpartum depression is one of the most common psychiatric disorders following delivery. This disorder may lead to serious problems for mother, child and family. Studies carried out on the prevalence of postnatal depression (PND) have reported varying rates ranged 5% to 40%. There have also been some conflicting findings in investigating its relative factors. The aim of this study was to determine PND and its risk factors in women referring to health care centers in Qom. Materials and Methods: During this cross-sectional study 300 women were surveyed 6-12 weeks following their delivery. Edinburgh Postnatal Depression Scale and Relative Factors Questionnaire were used for data gathering. Samples were assigned into two groups based on Edinburgh scores: ≥13 as depressed subjects, and <13 as non-depressed subjects. Finally, logistic regression was used for data analysis. Results: Totally, the prevalence of postpartum depression was found to be 23%. Among factors, unplanned pregnancy, newborn anomaly, dissatisfaction with husband, low income, lack of social support, crisis in the past year, previous history of depression, and previous postpartum depression were significantly associated with PND. Conclusion: We strongly recommend further emphasis on maternal mental health. It is also necessary to include mental health screening, supportive and consultative programs in post-natal routine health care, especially for at risk women.