A 60-year-old male with small-cell prostate carcinoma (SCPC) received external-beam radiotherapy of 60 Gy in 30 fractions and chemotherapy (cisplatin (CDDP) 80 mg/m2+ etoposide (VP-16) 100 mg/m2, six courses). Although fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) showed a complete response, local recurrence occurred in the gross tumor volume after 12 months after the end of chemoradiotherapy. Although the standard treatment for SCPC is not established because SCPC is a rare disease, radiotherapy for SCPC is necessary to study the optimal dose and irradiation area for local control.