A 53-year-old woman who underwent laparoscopic cholecystectomy for acute cholecystitis was discharged from the hospital after an uneventful postoperative course. However, she developed upper abdominal pain on the 6th postoperative day and was admitted to the hospital again with a suspicion of panperitonitis. Abdominal trial top found collection of biliary ascites. Postoperative biliary injury was likely. Endoscopic retrograde cholangiography disclosed leakage of contrast material from a communicating accessory bile duct which communicated between the cystic duct and the right hepatic duct. Bile leakage due to injury of the communicating accessory bile duct after cholecystectomy was diagnosed. Endoscopic nasobiliary drainage tube was placed and the conservative therapy was successful.The communicating accessory bile duct is an anomalous biliary structure which communicates between the major bile ducts and forms a circuit with the normal bile duct. In case the cystic duct is involved in a circuit, its cutting point must be determined after branching variation of the biliary tract is confirmed by preoperative examinations including DIC-CT.