A 78-year-old man had been admitted to a previous hospital because of epigastralgia and a diagnosis of cholecystolithiasis had been made. He had been transferred to our institution for further examination. CT scan and US revealed chronic cholecystitis and gallstone, however, ERC revealed severe obstruction of the cystic duct and EUS revealed dilation of that duct and a solitary mass there. Carcinoma of the cystic duct was diagnosed, and we performed cholecystectomy and resection of the extrahepatic duct with two-field lymphadenectomy. The pathological specimen showed a round flat elevated mass localized in the cystic duct. Histopathologically, the diagnosis was well differentiated tubular adenocarcinoma of the cystic duct with limy bile and tiny gallstone.