Background and aims: Depression is an affective (mood) disorder accompanied by the sense of disappointment, incompetence, sense of transgression, fear and sense of humility. Depression is the daily depressed-mood for two weeks. The aim of this study is analysis of the prevalence and effective factors on post-natal depression in women referring to Garmsar city health centers in 2015.Methods: This study is a descriptive and periodical study. The statistical population in this research includes the women who went to Garmsar city health centers during the second and third quarters in 2015, two months after their labor. The method of collecting data in this study was by census, and the data-collecting tool was Edinburg standard questionnaire for post-natal depression diagnosis. After collecting and re-controlling, the data were analyzed by SPSS 20 software package. Descriptive statistics (average and standard deviation) were used for describing the data. The analytical statistical tests (chi square and independent t-test) were used for the data analysis.Results: The findings showed that 40 out of 110 mothers were depressed (score of over 12), and the prevalence of post-natal depression mothers referred to Garmsar health centers was about 36%. The results indicated that there were no significant statistical relations between mother’s age, education, number of labor, types of childbirth, children’s sex, unwanted pregnancies, the history of sterility, and post-natal depression.Conclusion: Due to unpleasant effects of depression on the living qualities of mothers’ and the embryos’ and eventually the families, and due to its extensive prevalence in the city of Garmsar, precise identification of effective factors in emergence of this disorder seems to be essential. By awareness from its risk factors, some of the inevitable factors could be reduced or even confronted, and the relevant consequences can be reduced by timely and proper interventions.