Background: There is no study comparing schizophrenia and autism spectrum disorders (ASD) in terms of caregiver burden. Objectives: This study aims to compare the caregiver burden among family members of the patients with schizophrenia and ASD and investigate the predictive factors. Methods: A cross-sectional study with the family members living with and/or providing care to their patients was carried out. A sociodemographic form, the Beck Depression Inventory, the Self-Stigma Inventory for Families, and the Zarit Caregiver Burden Scale were utilized. Regression analyses were conducted to determine the predictive factors for higher burden. Results: Caregiver burden in ASD was significantly higher than in schizophrenia. Regression analysis showed that the predictors of high caregiver burden were the need for self-care (OR=3.6), self-destructive behaviors (OR=3.4), self-stigma (OR=1.1), depression (OR=1.1), and level of income (OR=1.0) for all family members. When the diagnosis was removed from the equation, the factors determining the high burden did not change. Conclusion: This study suggests that characteristics of the illness are stronger predictors than family members' characteristics in explaining high caregiver burden for both illnesses. Psychological, social, and economic supports should be provided for families to help alleviate their caregiving burden.