Background: Pregnancy is an important period in a woman's life cycle, often associated with changes in emotions and mood. Mental health disorders affect nearly one-fifth of pregnant women during the prenatal and postpartum periods. Some mental disorders that are often encountered are depression, anxiety, psychosis and post-traumatic stress. Objective: to find out the factors that influence the mental health of pregnant women at the Polanharjo Klaten Community Health Center. Research Method: Analytical survey with a cross-sectional time approach. The research sample was 83 pregnant women who visited ANC at the Polanharjo Klaten Community Health Center. Data collection tools used the DASS-21 questionnaire and the Multidimensional Scale of Perceived Social Support (MSPSS) questionnaire. Statistical tests use univariate, bivariate and multivariate analysis. Results: The mental health of pregnant women at the Polanharjo Klaten Community Health Center was 75.9% normal and 24.1% abnormal (anxiety). Factors that influence the mental health of pregnant women include education, gravida, social support and pregnancy history, while the factors age, occupation, maternal illness and planned pregnancy do not influence the mental health of pregnant women. Conclusion: Social support is the factor that has the most influence on the mental health of pregnant women at the