A 29-year-old man was admitted with right hypochondralgia and fever. Markedly dilated bile ducts were observed, mainly in the right lobe of the liver. Based on both the clinical findings and imaging, we diagnosed Caroli's disease and choledochal cyst complicated with cholangitis. Hepatocellular carcinoma (HCC) was also observed in segment 3, and the tumor measured 4cm in diameter. The patient was successfully treated with hepatectomy of the right lobe, partial hepatectomy of the left lateral lobe, and bile duct reconstruction. A histopathological examination revealed moderately differentiated HCC without any components of cholangiocellular carcinoma (CCC). Although Caroli's disease is complicated with CCC, a case of Caroli's disease complicated with HCC, as in the present case, is quite rare and therefore is considered to be worthy of reporting.