One of the main steps in saving the feet of diabetics is to take preventive measures in the form of foot care. Self-efficacy is one of the factors that can support the success of foot care in diabetics. This study aims to determine the relationship between self-efficacy and foot care behavior in patients with diabetes mellitus. The research method is quantitative with a cross-sectional approach. The sampling technique in this study is purposive sampling with a sample of 110 respondents. Data was collected using the Foot Care Confident Scale (FCCS) and Nottingham Assessment of Functional Footcare (NAFF) questionnaires. Data analysis in this study using the chi-square test. The results showed that 67 respondents (60.9%) had high self-efficacy and 43 respondents (39.1%) had low self-efficacy, 59 respondents (53.6%) had good foot care behavior, and 51 respondents (46.4%) had poor foot care behavior. The results of the chi-square test obtained a P-value of 0.000 < α = 0.05, which means that there is a relationship between self-efficacy and foot care behavior in patients with diabetes mellitus. It can be concluded that there is a positive relationship between self-efficacy and foot care behavior in diabetes mellitus patients at the Gandapura Public Health Center, Bireuen Regency. It is recommended that health workers can provide health education about foot care regularly in order to increase self-efficacy in people with diabetes mellitus.