A case of acute pancreatitis indued by the large impacted duodenal bezoar is presented. The patient under went antrectomy and a Billorth I Operation 3 years ago becuase of a perforated duodenal ulcer. An obstructing duodenal bezoar, measuring 10$ imes$6$ imes$4 cm in dimension, was impacted in the duodenal bulb and the 2nd portion of the duodenum. We suggest that a huge bazoar compressing the ampulla of Vater may be a mechanical factor predisposing acute pancreatitis.