Endocrine therapy for prostate cancer is androgen deprivation therapy and antiandrogens, which are the standard treatment for advanced prostate cancer. Endocrine therapy is effective in most prostate cancers, but as treatment continues, most patients eventually experience resistant to endocrine therapy and disease progression. Patients in this state are said to have castration-resistant prostate cancer. This review outlines the types of endocrine therapy for prostate cancer, the physiological mechanisms of endocrine therapy, its clinical use in Japan and the United States and Europe, new endocrine therapy for castration-resistant prostate cancer, and the side effects to be noted in endocrine therapy.