Superior mesenteric artery aneurysm is the third most common lesion and comprises approximately 5.5 % of all visceral artery aneurysms. The first successful repair was performed by DeBakey and Cooley in 1949. Since then, more than 100 cases have been reported. Fifty to sixty percent of these aneurysms are mycotic in origin. Other less frequent causes include arteriosclerosis, trauma, and medial degeneration. The operations are bypass with autologous tissue or with artificial vascular graft and aneurysmorrhaphy. We have experienced a case of superior mesenteric artery aneurysm which had undergone aneurysmectomy and artificial graft interposition. This is the first domestic case which was successful surgical repaired.