A 70-year-old male was treated for gastric ulcers. Follow-up upper gastrointestinal endoscopy revealed an irregular, elevated tumor in the second portion of the duodenum. Upon pathological inspection of a biopsy specimen, a diagnosis of adenocarcinoma was made, and the patient was admitted to our hospital. Computed tomography showed an irregular mass in the pancreatic head and dilatation of the main pancreatic duct and bile duct. Pancreatic head carcinoma with infiltration of the duodenum was diagnosed, and pylorus-preserving pancreaticoduodenectomy was performed. A histopathological examination of the resected specimen showed moderately differentiated adenocarcinoma in the minor duodenal papilla and chronic pancreatitis in the pancreatic head. Therefore, primary adenocarcinoma of the minor duodenal papilla with mass-forming chronic pancreatitis was diagnosed. Currently, the patient is alive without recurrence 17 months after the surgery. Primary adenocarcinoma of the minor duodenal papilla is extremely rare. We herein report this case, and also provide a review of the literature.