Priapism is defined as a full or partial erection for >4 hours without sexual stimulation or orgasm. Ischemic priapism is an emergency disease that urgently requires surgery to reduce pressure in the corpora cavernosa. We encountered a case of severe ischemic priapism that required a proximal shunt. The patient was a 71-year-old man who had been diagnosed with benign prostatic hyperplasia ; hence, oral administration of tamsulosin had been initiated at a local hospital. His penis became gradually rigid and presented with prolonged erection. Then he consulted our hospital. Penile aspiration was impossible, and phenylephrine injection was not effective. He was subsequently transferred to our hospital. He did not have severe pain but had complete erection. We could not correctly evaluate blood gas from the corpora cavernosa and color Doppler ultrasonography showed little blood flow in the corpora cavernosa. We judged that the patient had ischemic priapism. The erection could not be controlled by distal shunt plastic surgery performed using the T shunt and Al-Ghorab methods. Therefore, a proximal shunt plastic surgery as described by Sacher was performed. The surgery was effective, but it caused erectile dysfunction.