Inferior mesenteric artery aneurysm (IMAA) is a rare disease among visceral aneurysms. We encountered an open repair of IMAA in association with arteriosclerosis obliterans (ASO). The case was 74-year-old man who had progressive intermittent claudication for 10 years. Preoperative enhanced CT demonstrated IMAA and ASO due to the occlusion of right common iliac artery, the coil embolization was initially considered as a therapeutic option. However, since CT also revealed the occlusion of superior mesenteric artery, the open repair of the aneurysmal resection and subsequent IMA reconstruction were performed in order to avoid mesenteric necrosis. During the procedure, we confirmed bilateral arterial flow of the lower extremities and the good color of the small intestine before closing the abdomen. The patient was started on food intake on postoperative day (POD) 3, and CT showed intact arterial flow of the inferior mesentery. Postoperative course was uneventful and the patient was discharged on POD 16.