Objective Situations in which elderly people are the primary caregivers for their grandchildren are becoming more common. This study aimed to investigate moderating factors of and the association between grandchild care and the grandparents’ perceived health. Financial support in return for grandchild care was also investigated as a moderating factor. Methods Participants included 357 elderly people over the age of 60 years. The assessment to evaluate the perceived health status and social support was performed via a questionnaire. It included questions regarding the care of grandchildren and demographic variables, as well as the Medical Outcome Survey (MOS) 36-item short-form health survey (SF-36), and the MOS Social Support Survey (MOSSSS). Results The subscale scores of SF-36 and MOS-SSS did not differ significantly for grandchild-care status. However, the subscale scores of SF-36 were significantly higher in groups that received regular financial support from adult children in return for grandchild care than in groups that did not. Conclusion Our data suggest that regular financial support in return for grandchild care may be a moderating factor in the association between grandchild care and the perceived health status of elderly people. These findings have important social implications and warrant future study to reveal the psychological mechanism of these associations and enhance the health of elderly individuals.