We report a case of bleeding in the small intestine of a 59-year-old man that was successfully diagnosed and treated by total intraoperative enteroscopy. The patient was admitted to our hospital because of gastrointestinal bleeding. Gastroscopy, colonoscopy and mesenteric arteriography could not identify the bleeding point. Technetium-99m-labeled red blood cell scintigraphy suggested bleeding from the small intestine but could not reveal the precise lesion. As the patient presented melena and went into a state of shock, we performed emergency laparotomy with total intraoperative enteroscopy using a colonoscope. A small ulceration was found at the jejunum, and subsequently partial resection of the jejunum was performed. The lesion was diagnosed histopathologically as angiodysplasia. The patient recovered uneventfully and was discharged on the 24th postoperative day. Bleeding in the small intestine is rare and difficult to diagnose but it sometimes induces a severe condition. Total intraoperative enteroscopy using a colonoscope is effective for detecting the bleeding point in the small intestine and can be performed at most centers without special fiberscopes and techniques.