Hemosuccus pancreaticus (HP) is mostly induced by a ruptured pseudoaneurysm or hemorrhage from a pseudocyst in chronic pancreatitis. We herein report a rare case with HP induced by tumor hemorrhage. The present patient is a 71-year-old woman referred to us with a diagnosis of severe progressive anemia. Endoscopy revealed hemorrhage from the papilla of Vater. Computed tomography showed a multilocular cystic tumor in the tail of the pancreas. The patient underwent a distal pancreatectomy. The histopathological diagnosis was carcinoma in mucinous cystadenoma. No cancer infiltration into the pancreatic duct was detected. Pancreatography of the resected specimen demonstrated an overt communication between the main pancreatic duct and the cystic cavity of the tumor, which was not demonstrated preoperatively by endoscopic retrograde pancreatography. Although the cause of HP is mainly acute or chronic pancreatitis, we should bear in mind that a pancreatic tumor may be a possible cause of HP and that, as such, prompt and proper treatment is mandatory.