Genomic tumor profiling tests (GTPTs) to find molecular targeted drugs for patients with advanced cancer are being introduced into clinical settings, which may result in secondary germline findings. Although small-scale qualitative studies have revealed patients' attitudes toward GTPTs and preferences on receiving germline findings, no large-scale quantitative research exists that includes family members. We conducted anonymous surveys with 757 cancer patients (CPs), 763 family members (FMs), and 3697 general adults (GAs) in Japan. Awareness of GTPTs was low in all groups, however, both CPs and FMs showed a higher degree of recognition in the benefits of GTPTs. FMs wanted information on germline findings to be shared more than the CPs. Since advanced CPs may have psychological burdens that make it difficult to express their opinions on their therapeutic options and sharing germline findings, GTPTs should be offered with advanced care planning for patients.