Double common bile duct (DCBD) is a rare congenital anomaly among biliary anomalies. The anomaly has an important clinical implication because of its association with anomalous pancreaticobiliary ductal union (APBDU) and upper gastrointestinal cancers. In addition, if one of the two common bile ducts is mistaken for the cystic duct during surgery, bile duct injury is likely to occur. Treatment depends on the coexistence of concomitant cancer and APBDU. A 54-year-old male diagnosed of gastric cancer was referred for surgery. During surgery, we incidentally detected bile leak from the tubular structure around the hepatoduodenal ligament. We performed intraoperative cholangiogram by cannulizing into the tubular structure, and confirmed the tubular duct as the accessory bile duct with an ectopic drainage into the stomach, which was connected to the proximal common bile duct. In this study, we report a rare case of DCBD with an ectopic drainage into the stomach and review the literature.