Duodenal carcinoid tumors are rare, and they represent only 2.0~8.9% of all gastrointestinal carcinoid tumors in the western countries. Duodenal carcinoid tumors have previously been treated by surgical resection. The recently recommended treatment for a carcinoid tumor smaller than 1 cm in diameter is endoscopic resection. We experienced a case of a duodenal carcinoid tumor in a 56 year-old man who presented with upper abdominal pain. On the endoscopic examination, a 6 mm sized polypoid lesion with a central depression was noticed on the duodenal bulb. The biopsy confirmed the diagnosis of carcinoid tumor. The endoscopic ultrasound probe showed a hypoechoic tumor that was confined to the submocosal layer. The tumor was completely resected by an endoscopic mucosal resection technique and using a transparent cap.