Introduction: Well‐being is an important component of health, while informal care plays a vital role in daily care of the elderly. However, the effects of informal care on the well‐being of the elderly remain unclear. This study was aimed to estimate such effects, in which well‐being was measured by 2 subjective indicators: happiness and life satisfaction. Methods: Potential endogeneity was purified using instrumental variables. Data were collected from national baseline China Health and Retirement Longitudinal Study (CHARLS). Results: Receiving informal care would decrease the elderly's happiness score and life satisfaction score significantly. The health produced from informal care cannot offset the health depreciation caused by aging. Discussion To improve the well‐being of the elderly, caregivers have more to do and policymakers can design designated care policies based on our results.