A 71 -year-old man was referred to our hospital because of repeated bowel obstruction. He had previously undergone cystectomy with ileal conduit urinary diversion for the treatment of bladder cancer at the age of 28 years. Computed tomography revealed a mass in the ascending colon. Ileostomy was initially performed because of poor general condition that improved with postoperative nutrition management. Enema findings revealed ascending colon cancer and we therefore decided to perform curative surgery. Intraoperative findings revealed that the ascending colon cancer had invaded the ileal conduit. However, it was confirmed that the ureter-ileal conduit anastomosis and the mesentery of the ileal conduit could be preserved. We performed right colectomy and partial resection of the ileal conduit with curative intent. The pathological stage was pT4bpN0cM0, pStage II. There were no signs of recurrence 15 months after curative surgery.