We report a case of prostate cancer in a 45-year-old. The patient was found to have an elevated prostate specific antigen (PSA) level at a general health check and was referred to our division. Serum level of PSA was 6.9 ng/ml. Digital rectal examination and magnetic resonance imaging revealed a small nodule on the right lobe. Transperineal needle biopsy of the prostate revealed adenocarcinoma at the bilateral lobe (Gleason score 3+4). Computed tomography and a bone scan showed no evidence of metastasis. The patient was diagnosed as cT2b, NO, MO, and underwent a radical prostatectomy. Patients younger than 45 with prostate cancer are rare, although the incidence of prostate cancer is increasing. Here, 25 cases previously reported in Japan in addition to the present case, are reviewed.