Segmental arterial mediolysis (SAM) is a rare, nonatherosclerotic, noninflammatory arteriopathy. A 52-year-old man with sudden hemiparesis of the right side was found to have an aneurysm of the left internal carotid artery and concomitant multiple aneurysms of the extrahepatic, celiac, and superior mesenteric arteries. Reconstructive operations using autologous vein graft were performed to treat the aneurysms. The histopathology analyses of resected arterial and aneurysmal specimens showed characteristics consistent with SAM. To our knowledge, a successfully treated case of SAM affecting both the carotid artery and visceral arteries has not previously been described.