Kin altruism has been widely observed across species, including humans. However, few studies have discussed the development of kin altruism or its relationship with theory of mind. In this study, 3- to 6-year-old children allocated resources between themselves and kin, a friend, or a stranger in three allocation tasks where the allocation either incurred a cost, incurred no cost, or conferred a disadvantage. The results showed that, compared with 3- and 4-year-olds, 5- and 6-year-olds acted more altruistically toward kin and that kin altruism was uncorrelated with theory of mind. These findings suggest that, within the context of resource allocation, kin altruism emerges toward the end of early childhood and probably differs from other prosocial behavior that relies solely on the understanding of others' perspectives.