A 75-year-old man, with a past history of radiation therapy for prostatic carcinoma ten years ago, was referred to our hospital with complaints of penile tumor. After pathological examination by core biopsy, the patient was treated by radical penectomy for a penile tumor. Pathological examinations demonstrated that the tumor was composed of pleomorphic spindle cells without any differentiation tendency and diagnosed as spindle cell sarcoma. Although the patient had a past history of radiation therapy for the prostate, the causal relation of development of penile sarcoma with the radiation therapy was uncertain because the main tumor was very near but outside of the irradiation field. The sarcoma rarely occurs in the penis, and this is the first report of penile spindle cell sarcoma, to our knowledge.