Carcinoma of the minor duodenal papilla is extremely rare. We present the case of a 69-year-old man diagnosed with a tumor of the second portion of the duodenum by upper gastrointestinal endoscopy, which revealed a 1.5-cm elevated tumor with slight ulceration at the minor duodenal papilla. Biopsy revealed adenocarcinoma, and a computed tomography scan showed an enhanced tumor in the duodenum, with no abnormality in the pancreatic head. A pancreas-sparing segmental duodenectomy was performed, and the duodenum reconstructed with an end-to-end anastomosis. Microscopically, the tumor was a well-differentiated adenocarcinoma, with no infiltration at the cut end of the accessory pancreatic duct. The postoperative course was uneventful and the patient discharged on postoperative day 11. We reviewed previously reported cases of carcinoma of the minor duodenal papilla. Early and exact preoperative diagnosis of duodenal neoplasms makes it possible to select a less invasive treatment, which also maintains curability.