BACKGROUND: There are limited treatment options for advanced non-melanoma skin cancers (NMSCs). To overcome this issue, we need to conduct clinical studies, however, there is a lack of information on how many patients with advanced NMSCs are treated annually in Japan. OBJECTIVE: To investigate the actual number of advanced NMSC patients in Japan. METHODS: A questionnaire survey was sent to 668 institutes to educe information on: 1) the numbers of patients with squamous cell carcinoma (SCC), extramammary Paget disease (EMPD), other skin origin carcinomas, and cutaneous angiosarcoma (CAS) admitted in 2016 and 2017; 2) the preferred first- and second-line chemotherapies; and 3) the anticipated for future development. RESULTS: Questionnaires were returned from 383 (57.3%) institutes. They reported a total of 1765 patients over the 2 years. The annual number patients with SCC, EMPD, other skin carcinomas, and CAS was 323.5, 192.5, 126, and 240.5, respectively. We estimated the annual number of patients for all 668 institutes to be 1255.6. Current first- and second-line treatment for NMSCs were chemotherapy regimens, but immune checkpoint inhibitors were the most anticipated new drugs for SCC and CAS, while chemotherapy was still the most anticipated treatment for EMPD. CONCLUSION: Considering that during 2017, the number of deaths in Japan due to NMSC was reported to be 948, our estimated annual number of patients with NMSCs, 1255.6 seems to be an accurate estimation. As most of the treatment options for advanced NMSCs are outdated, the results of this study should be used to propose clinical studies.