Postpartum depression is a harmful depression risk; if not treated properly, it can have bad consequences for both mother and child. Hence, efforts are needed to prevent postpartum depression in pregnant women. This article aims to describe and find out the effect of self-help psychological intervention on the knowledge and attitudes of pregnant women in preventing postpartum depression. This article was quantitative research with a quasi-experimental model. The study population was 155 pregnant women in the Darussalam Public Health Center working area in Aceh Besar, 2021. The sample was 74 respondents, with 37 in the intervention group and 37 in the control group. Data was collected using The Knowledge about Postpartum Depression Questionnaire (KPPD-Q) and Attitudes Toward Postpartum questionnaires. This study found that the self-help psychological intervention significantly affects the knowledge and attitudes of pregnant women (p-value = 0.000 <0.05). Also, there were significant differences in knowledge and attitudes between the intervention. This study concluded that Self-help Psychological interventions could ascend pregnant women's knowledge and attitudes toward preventing postpartum depression. Respondents' age, education level, and gestational age are the driving factors for increasing knowledge and attitudes.