A 71-year-old woman presented with jaundice was seen at a local hospital. Magnetic resonance cholangiopancreatography (MRCP) revealed dilation of the common bile duct and a mass at the duodenal papilla. Esophagogastroduodenoscopy revealed a type I p tumor on the cylindrical epithelial side of the esophagogastric junction and a tumor in the duodenal papilla. She was referred to our hospital with a diagnosis of esophageal and duodenal papilla adenocarcinoma. Contrast-enhanced CT scan showed lower thoracic esophageal wall thickening, an enhanced mass in the duodenal papilla, and an esophageal hiatal hernia. We planned lower esophagectomy, total gastrectomy, and pancreatoduodenectomy after hernia repair through the abdominal cavity with the diagnosis of double cancer comprising cancer of the esophagogastric junction and cancer of the duodenal papilla. The proximal edge of the tumor was at the level of the lower pulmonary vein, although we repositioned the esophagogastric junction to the abdominal cavity side. We performed lower esophagectomy with additional right thoracotomy, total gastrectomy, and pancreatoduodenectomy because the transhiatal approach was difficult. Macroscopic examination of the resected specimen revealed Barrett's epithelium with a type Ip tumor in the esophagus and an ulcerative-predominant type tumor in the duodenal papilla. Pathological examination revealed Barrett's esophageal adenocarcinoma (fT1bN0M0 Stage I) and duodenal papilla cancer (fT2N0M0 Stage II). Synchronous double cancer comprising Barrett's esophageal cancer and duodenal papilla cancer is rare. We herein report a simultaneous operation in a patient with these cancers.