A 76-year-old man with a mass on the penis and a pain during nighttime erection was referred to our institution. T2-weighted magnetic resonance imaging showed a high-intensity area in the dorsal part of corpus cavernosum. We diagnosed him with the abscess of corpus cavernosum. Surgical drainage and chemotherapy had been performed for 3 years. However, it recurred consistently and developed several cutaneous draining fistulae. The abscess culture was sterile. Skin biopsy revealed a diagnosis of penile pyoderma gangrenosum, which was treated successfully with prednisolone and an immunosuppressive drug. Twenty nine cases of the abscess of corpus cavernosum have been reported in the literature. Most of the recurrent cases tend to be idiopathic corpus cavernosum abscess with sterile culture and finally penectomy is performed. Based on this case, we propose a new notion that corpus cavernosum abscess can be an early symptom of pyoderma gangrenosum.