A 73-year-old man who had undergone right common iliac-right femoral-left femoral artery bypass, and left femoral-popliteal artery bypass at 60, and stent graft for abdominal aortic aneurysm at 69, had a pseudoaneurysm repaired at the left femoral artery anastomosis site at 72. Retention of fluid continued around the prosthesis, so drainage and sartorius muscle flap were carried out at 72. Due to the occlusion of the left popliteal bypass, a cross over bypass was performed from the right iliac artery position to the left above knee popliteal artery through the left obturator foramen route. One month later, CT revealed that the prosthesis had penetrated the bladder. In open surgery, the bladder was incised, and the prosthesis was taken out of it. The postoperative course was uneventful. Oral antibiotics were continued for 3 months. Currently, there are no signs of infection. There are very few opportunities to choose an obturator foramen route. It was necessary to identify the bladder wall under direct vision with great care.