This case report describes an 83-year-old man with intrahepatic cholangiocarcinoma who was referred by a local hospital. Abdominal computed tomography (CT) showed a large tumor in hepatic segments 4, 5, and 8 involving the right hepatic vein and inferior vena cava, which is normally indicative of an unresectable locally advanced tumor. After systemic chemotherapy with gemcitabine and cisplatin, the observed decrease in the level of tumor marker suggested that the cancer was responding to treatment, while radiological findings showed the main tumor shrunk without the presence of distant metastases. Thus, hepatic left trisectionectomy with bile duct resection was performed after portal vein embolization. Pathological examination revealed negative margins (R0). Eighteen months after surgery, the patient is free of disease and shows no signs of recurrence. An initially unresectable, locally advanced biliary tract cancer may be down sized by chemotherapy, which makes radical resection possible, at least in a proportion of patients. This approach provides longer survival and may have a potential for disease eradication as a new multidisciplinary approach for patients with unresectable locally advanced biliary tract cancer.