A 69-year-old man was accidentally found to have an abdominal aortic aneurysm (AAA) by screening CT scan during hospitalization in the department of neurosurgery in our hospital for cerebral infarction, and he was referred to the department. On abdominal CT scan, Mantle sign was not evident. Preoperative endoscopic examination demonstrated type II cancer of sigmoid colon. Staged approach was scheduled, and the patient underwent sigmoidectomy and D1 lymph node dissection at first. The histological diagnosis was moderately differentiated adenocarcinoma without invasion to the serosa or involvement of lymph node and diagnosed as in Stage II. Thirty-six days later, the AAA was repaired via a retroperitoneal approach. The aortic wall seemed white pottery and the histopathological diagnosis was inflammatory abdominal aortic aneurysm. This case of inflammatory abdominal aortic aneurysm with colonic carcinoma is reported because of the rarity, together with some review of literatures.