Cholecystohepatic duct (CHD) is a very rare anomaly of the extrahepatic biliary tract. Herein we report on a case of bile leakage after cholecystectomy due to injury to the CHD, the presence of which had not been recognized before surgery. Follow-up computed tomography (CT) of an asymptomatic 63-year-old man 1 year after Roux-en Y reconstruction for advanced gastric cancer revealed a gallbladder mass, and so cholecystectomy was planned. Preoperatively, there was no indication of biliary anomaly by magnetic resonance cholangiopancreatography (MRCP). During surgery, a "string" was visualized between the cystic duct and the bed of the gallbladder. This "string" was ligated without intraoperative cholangiography and the gallbladder was removed. On postoperative day (POD) 5, bile peritonitis developed and percutaneous drainage was performed. Abdominal contrast examinations from the drainage tube enabled visualization of the intrahepatic duct of the posterior segment of the liver. Careful re-examination of preoperative MRCP images showed a confluence between the bile duct and the neck of the gallbladder (i.e. a CHD), which drained the posterior segment of the liver. Although the end of the CHD was blind, the bile leakage improved following percutaneous abdominal drainage alone, without percutaneous transhepatic cholangiodrainage or reoperation. In conclusion, CHD is a very rare biliary anomaly. However, it should be kept in mind during cholecystectomy to avoid serious complications.