Pancreas divisum is the most common congenital anomaly of the pancreas. Whether pancreas divisum is the cause of chronic abdominal pain, acute pancreatitis, or chronic pancreatitis is a matter of controversy yet. We recently experienced a case of acute pancreatitis due to an impacted stone at the orifice of the minor papilla in a 58 year-old man with pancreas divisum who showed clear radiologic evidences of dorsal chronic pancreatitis. The bout of acute pancreatitis recovered rapidly after endoscopic treatment (minor papilla sphincterotomy, stone removal, and endoscopic nasopancreatic drainage). We herein report an unusual manifestation of pancreas divisum in which endoscopic treatment was effective.