Background: There is a consensus that cancer care should go beyond physical care as cancer patients and their family caregivers experience psychological burden, financial difficulty, as well as social relation issues. The current study aimed to investigate the moderating impact of social support on depression and anxiety of cancer patients and their family caregivers.; Methods: Gastric cancer patients and their family caregivers who visited a university medical center in Seoul were approached for participation in the study. Fifty-two pairs of adult patients and caregivers participated in the study. Along with demographic information and the physical condition of the patients, such as pre-operation cancer stage and the type of gastrectomy, social support, depression, and anxiety were measured for patients and caregivers, respectively.; Results: In the first round of analysis, patients' depression was associated with age, while patients' anxiety was related to income. On the other hand, caregivers' depression was not associated with patients' health and living arrangement. In the second round of analysis to examine the moderating effect of social support, patients' income and social support were related to depression and anxiety, but the interaction of income and social support was only observed for anxiety. For caregivers, no interaction effects were found. Social support decreased the negative effects of low income status on the patients.; Conclusion: While the income of the families with cancer cannot be adjusted in the short-term, their experience of social support can be managed by a proper support system. Diverse implications in medical settings are discussed.