An 18-year-old man was admitted to a local hospital with abdominal pain and bloody stool. Upper and lower gastrointestinal endoscopy failed to show any bleeding sites; however, an angiography of the superior mesenteric artery done on hospital day 4 showed an abnormal artery with an aneurysm, branching from the ileal artery. This artery was thought to be the vitellointestinal artery, a feeding artery of Meckel diverticulum. After embolization, he was transferred to our hospital, where we performed emergency laparotomy with partial resection of the ileum, including a bleeding Meckel diverticulum. Pathological examination revealed ectopic gastric mucosa and peptic ulceration, which we assumed was the origin of the bleeding. The patient had an uneventful postoperative course. Visceral artery aneurysms are rare but important vascular lesions because of their potential for fatal rupture. Although a minimally invasive procedure can be performed for a vitellointestinal artery aneurysm in patients with asymptomatic Meckel diverticulum, we treated our patient surgically because he presented with hemorrhagic shock and had been unresponsive to an H(2)-receptor antagonist.