A 53-year-old man presented to our hospital with a few-month history of fatigue and anorexia. His aging male's symptoms (AMS) score was 57, and the free testosterone value was low (6.5 pg/ml). He was diagnosed with severe late-onset hypogonadism indicative of androgen replacement therapy (ART). His serum prostate specific antigen was 8.7 ng/ml, and pelvic magnetic resonance imaging showed a low intensity area in the peripheral zone of the prostate. A systematic 10-core prostate biopsy revealed one core of adenocarcinoma with a Gleason score of 3 + 3=6. Imaging examination revealed organ-confined prostate cancer that was cT2aN0M0. Given his desire for ART for the treatment of hypogonadism, the patient underwent open radical prostatectomy. Pathologic examination demonstrated prostate adenocarcinoma that was pT2aN0, and Gleason score of 3 + 3=6. After confirming that the prostate specific antigen value was under 0.01 ng/ml for three years after prostatectomy, the patient received 125 mg methyltestosterone monthly. His hypogonadism-related symptoms diminished and AMS score dropped to 48. During a three-year follow-up of ART, no biochemical recurrence was found.