A 38-year-old woman was hospitalized in August 2007. This visit was her fifth episode of acute pancreatitis. Computed tomography revealed a cystic structure located near the antrum. Communication between this structure and the pancreatic duct was revealed by endoscopic retrograde cholangiopancreatography. Ultrasonography revealed that the cyst wall had a layered structure. Thus, we regarded it as a gastric duplication cyst. We thought that the gastric duplication cyst communicating with an aberrant pancreatic duct was responsible for the recurrent acute pancreatitis. In August 2008, a cyst gastrostomy was performed between the gastric duplication cyst and the stomach. No recurrence of acute pancreatitis has since occurred.