A woman in her seventies was admitted because of black stool. Esophagogastroduodenoscopy and colonoscopy revealed no bleeding lesions. Balloon endoscopy showed a long and slender polyp. The polyp was covered with normal mucosa and accompanied with ulcerations. The long polypoid lesion was found to be located in the duodenojejunal flexure by a small bowel series. We performed endoscopic polypectomy. The polyp was composed of edematous mucosa and submucosa with dilated blood vessels and lymphangiectasia. The histologic findings of resected specimen were compatible with colonic muco-submucosal elongated polyp. The polyp was considered to be classified as enteric muco-submucosal elongated polyp.