We report a case of ectopic hepatocellular carcinoma arising in the bile duct. A 72-year-old woman was transferred to our hospital with fever, abdominal pain, and jaundice. Contrast-enhanced computed tomography revealed a round mass, measuring 25 mm in diameter, in the bile duct. The mass was causing obstructive jaundice. Endoscopic retrograde cholangiography showed a 27 mm x 21-mm round defect in the superior bile duct. These findings led to a diagnosis of bile duct tumor, and the patient underwent extrahepatic bile duct resection and biliary reconstruction. Gross examination of the tumor showed a fibrous capsule and a stalk arising from the bile duct mucosa. The tumor was diagnosed histopathologically as well-differentiated hepatocellular carcinoma arising in the bile duct.