Annular pancreas is a rare congenital anomaly. We report a case of relapsing acute pancreatitis localized in the annulus of an annular pancreas in a young child. A 6-year-old boy complained of abdominal pain and we made a diagnosis of acute pancreatitis based on blood biochemistry results. Over the subsequent 12 months, he experienced two more pancreatitis-like attacks. Endoscopy revealed a duodenal stenosis in the second portion of the duodenum. Ultrasound, computed tomography, and magnetic resonance imaging depicted a ring of pancreatic tissue encircling the duodenum with a duct in the tissue, manifesting dilatation with a characteristic circular pattern around the duodenum. No dilatation of the dorsal pancreatic duct or pancreatic divisum was found. Based on these findings, we diagnosed acute pancreatitis localized in an annulus in an annular pancreas. This case report suggests that an annular pancreas may predispose to localized relapsing acute pancreatitis even in a child.