A 48-year-old man, who had suffered a bout of acute pancreatitis in September 2000, was found in March 2001 to have an increased concentration of serum amylase. A tumor in the pancreas body associated with stenosis and prestenotic dilatation of the main pancreatic duct was detected using imaging techniques. Distal pancreatectomy was performed under the diagnosis of pancreatic carcinoma. An intrapancreatic hematoma due to rupture of a pseudoaneurysm of the intrapancreatic artery was found in the resected specimen. This case illustrates how difficult it is to diagnose a small cancerous tumor in the pancreas and the rare presentation of this intrapancreatic pseudoaneurysm, which developed in a patient with a recent history of acute pancreatitis.