Objectives: To clarify how the care burden of primary family caregivers is associated with social cohesion in an urban area of Tokyo, Japan.Study designCross‐sectional study. Methods: A questionnaire survey of primary family caregivers was conducted in Tokyo in 2015. Social cohesion was examined using the social capital indicators of Kondo et al, and the care burden of primary family caregivers was assessed by the Zarit Care Burden Interview Scale in Japanese short version (J‐ZBI_8). Data were analyzed by multiple regression models. Ethics approval was obtained to carry out this research. Results: Seventy‐nine caregivers responded to the questionnaires. After excluding 6 caregivers who did not respond appropriately to the questionnaire, 73 caregivers were included in the analyses. The average age of the primary family caregivers was 68.9 ± 12.7 years old, and that of the patients receiving care was 83.1 ± 10.0 years old. “Receipt of instrumental support” was significantly associated with reduced burden of care for family caregivers as assessed by the J‐ZBI_8 score (P = .027). Conclusion: This study suggested that social cohesion was significantly associated with reduced burden of care for primary family caregivers. Especially, the results suggested that “social support: receipt of instrumental support” was associated with a lower burden of care after adjustment for confounding factors. It is important to understand family structure and social community differences such as informal social support for future policy making.