Pancreatic cancer is a rare cause of gastrointestinal bleeding, and it is extremely rare for hematemesis to be the initial manifestation of invasive pancreatic cancer. We report the case of a 67-year-old man with hematemesis who was found to have invasive pancreatic cancer with a bleeding duodenal ulcer. The patient was not icteric, but repeated sudden hematemesis. An urgent pancreatoduodenectomy was performed with a favorable outcome. Microscopic examination revealed that an adenocarcinoma originating from the pancreatic head extended to the muscularis propria of the duodenum. Furthermore, an exposed vessel and narrow fistula were found. The diagnosis, pathological findings, preoperative events, and postoperative outcome in this unusual case are reviewed.