A 71-year-old woman with pan-peritonitis was transferred to our hospital. Imaging studies showed the extravasation of contrast medium from the bladder to the intraperitoneal cavity, the right non-visualizing kidney and the left hydronephrosis. Cystoscopy revealed bladder stones and a fistula at the posterior wall of the bladder. A histological examination of specimen around the fistula revealed squamous cell carcinoma(SCC) with stromal invasion. Symptoms of peritonitis subsided following the placement of bilateral ureteral catheters and a urethral catheter. Because a laparotomy revealed peritonitis-carcinomatosa, she underwent bilateral ureterocutaneostomies, the removal of the bladder stones and the primary closure of the fistula. She died on the 42nd day after surgery.