Caregiving burden significantly effects the physical and mental health of family dementia caregivers. While the association between objective caregiving burden (OCB) and subjective caregiving burden (SCB) of family dementia caregivers is well documented, little is known as with how the association is moderated by the configuration of intrapersonal resource (e.g., immanent justice reasoning) and interpersonal resource (e.g., social support). The present study collected cross-sectional data on 157 major family caregivers of non-institutionalized persons with dementia in an urbanizing region of Western China’s Sichuan Province. They responded to questions on daily time spent on caregiving, the short version of Zarit Burden Interview (ZBI), a sub-scale of a caregiver meaning scale, Social Support Rating Scale (SSRS), and demographic questions. Controlling for the demographic variables of the caregivers, this study found that the objective and subjective dementia caregiving burden were significantly associated (p < 0.001), and immanent justice reasoning was positively correlated with subjective burden (p < 0.01). Moreover, the association between OCB and SCB was significantly positive when social support and immanent justice reasoning were both high (p < 0.001), but neutral when social support was high and immanent justice reasoning was low. The association between OCB and SCB was significantly positive when social support and immanent justice reasoning were both low (p < 0.05), but neutral when social support was low and immanent justice reasoning was high. This research suggests the importance of developing intervention programs that consider the configuration of the external supporting resources and internal meaning-making of caregiving of the family dementia caregivers.