Objectives: This study examines the post-traumatic growth (PTG) of bereaved families who care for cancer patients and related factors in Japan. Methods: Participants included 1298 members of bereaved families of cancer patients (aged 20 or older). An anonymous self-administered questionnaire on PTG, coping, and social support was mailed to 496 bereaved families who provided written informed consent. Results: Responses were obtained from 476 bereaved families; however, since 28 families had missing data, 448 were included for the analyses.