Most malignant tumors originating from the biliary tract are adenocarcinomas, and adenosqamous carcinoma of Klatskin's tumor is a very rare finding. An 83-yr-old man was admitted to our hospital because of jaundice. The abdominal computed tomography and magnetic resonance cholangiopancreatography revealed wall thickening and luminal stenosis of both the intrahepatic duct confluent portion and the common hepatic duct. These findings were compatible with Klatskin's tumor, Bismuth type III. Considering the patient's old age, palliative combined modality therapy was performed. After percutaneous transhepatic biliary drainage, biopsy was performed via percutaneous transhepatic cholangioscopy. The histopathologic findings showed adenosquamous carcinoma. External radiotherapy and intraluminal brachytherapy through the endobiliary Y-type stent were then done. Nine months after the radiotherapy, the laboratory findings and the abdominal computed tomography revealed biliary obstruction and progressive hepatic metastasis. The combined modality therapy of external radiotherapy, intraluminal brachytherapy and stenting assisted him to live a normal life until he finally experienced biliary obstruction.