The effectiveness of Maternal Mental Health Education with the Psychological Adaptation Theory approach to Breastfeeding Self Efficacy (BSE) and Postpartum Mother Stress. This research method is intervention research using a quasi-experimental design through a pretest and post-test design with a control group. The sample in this study were pregnant women in their third trimester who checked themselves at the Community Health Center, met the inclusion criteria, were willing, and had signed informed consent 82 samples. The analysis results using the chi-square test for self-efficacy variables before treatment obtained a value of p = 0.021, and after the intervention, the value of p = 0.001. Before treatment, the value of p = 0.185 > 0.05 was obtained for stress which showed no significant difference. Maternal mental health education that has been developed is proven to increase pregnant women's self-efficacy and reduce stress in postpartum mothers. Therefore, the need for education to be applied in midwifery services, especially for postpartum mothers.