Objective We examine the effects of filial norms and co‐residence as well as patterns of social exchange on support that adult children give to their parents and in‐laws in Japan. Methods We estimate ordered logit models with data from the Japanese General Social Survey. Results Children who receive money from their parents are more likely than those who receive no such support to give their parents nonmonetary support, while children who receive nonmonetary support from their parents are more likely to assist their parents financially. Receiving money from in‐laws is reciprocated with nonmonetary and monetary support. Filial norms increase the level of monetary support to parents and in‐laws, especially for men. Co‐residence increases monetary and nonmonetary support from children to parents and in‐laws, while the positive effect of co‐residence on nonmonetary support from children to in‐laws is limited to women. Conclusion Notions of social exchange as well as filial norms and co‐residence encourage intergenerational support in Japan.