The purpose of the present study was to develop the Social Support Questionnaire for Family Caregivers. Subjects were family caregivers, ranging in age from 32 to 90 years, living in Isehara City, Kanagawa Prefecture. The survey was carried out in 2011, and 450 persons responded (a response rate of 53.7%). Structural equation modeling was used to test a measurement model and three structural equation models. The results indicated that construct validity of third-order factor model was confirmed. The model was composed of 15 observed indicators, 5 first-order factors, 2 second-order factors, and 1 third-order factor. The first-order factors were emotional support from kin, instrumental support from kin, emotional support from non-kin, instrumental support from non-kin, and emotional support from care-receiver. The second-order factors were kin support and non-kin support. The third-order factor was overall social support. The reliability (Cronbach’s alpha coefficient) of 7 subscales and the overall scale were sufficient. Seven-eighths of all scales significantly correlated with the score for CES-D. The scale would significantly contribute to the measurement of social support for family caregivers.