Conventional preoperative imaging has limited modality and accuracy in primary intrahepatic cholangiocellular carcinoma (ICC) in the caudate lobe (CL). Furthermore, estimating resectability and tumor extension from preoperative imaging is inaccurate. A 60-year-old patient with ICC administrated in our institution requested a second opinion. His lesion was judged unresectable hilar cholangiocellular carcinoma because it had spread widely to the bilateral lobe of the liver as shown by preoperative imaging studies. The irregular shaped mass was located in the para-caval portion of the CL and the size as shown by computed tomography (CT) was 40mm in diameter. The tumor extended close to the common hepatic artery and the right portal branch was involved. The left lobe showed marked atrophy and intrahepatic biliary duct (IHBD) dilatation of the whole liver was observed. The tumor was mainly located in the proximal side of the left lobe and every IHBD were interrupted in the porta hepatis by magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiography. However, the resectability of this tumor could not be determined from these imaging studies. Three-dimensional imaging by multidetector CT (3D-CT) revealed that the tumor involved the left hepatic artery and portal branch whereas the right hepatic artery was intact. The patient was successfully treated in surgery by extending the left lobectomy with en bloc caudate lobectomy. The 3D-CT imaging study was helpful in assessing the resectability in ICC of CL.