An elderly woman with a history of cholecystectomy and a re-operation for postoperative peritonitis underwent extracorporeal shock wave lithotripsy (ESWL) for right and left renal pelvic calculi, 11 ¥ 6 and 12 ¥ 5 mm in size, to which 2400 and 1400 shots at 20 kV were given, respectively, on the same day. During the evening after the operation, the patient started to complain of upper abdominal pain. Laboratory examination on the next day revealed elevations in blood and urine amylase levels and a diagnosis of pancreatitis was made. Conservative treatment, including administration of protease inhibitor, did not improve her symptoms; abdominal distension became marked and she underwent laparotomy. Necrosection and indwelling of several drain tubes in abdomen were performed with an operative diagnosis of acute necrotic pancreatitis. With daily irrigation of drain tubes and treatment for methicillin-resistant Staphyloococcus aureus infection of the lungs and abdominal cavity, septicemia and duodenal fistula, the patient gradually recovered and was discharged on postoperative day 151. It was suggested that ESWL was responsible for the acute pancreatitis. Either an obstruction of the pancreatic duct by fragments of common duct stone, or mechanical injury of the pancreas due to adhesion between the pancreas and surrounding tissue caused by the lapalotomy, was considered as a possible cause of pancreatitis. To our knowledge, there has been no previous report of severe acute pancreatitis and the present case suggests that ESWL may cause severe pancreatic even in cases without stone shadow in the bile, common duct or pancreatic duct.