A 59-year-old man with fever was referred to our hospital under a diagnosis of liver abscess. The laboratory data showed mild leukocytosis and elevated serum level of C-reactive protein. Abdominal enhanced CT and MRI showed a mass of 45 mm in size, demonstrating an early ring-like enhancement, in the anterior segment of the right hepatic lobe. The patient eventually underwent hepatic resection not only because his clinical condition did not improve even after percutaneous drainage but because his serum CA 19-9 levels showed an increasing trend. The surgically resected liver revealed a relatively well-defined grayish-white solid mass showing extensive central necrosis and infiltrative growth margin. Histopathological examination revealed a diffuse proliferation of oval or short spindle-shaped neoplastic cells, and immunostaining confirmed the final diagnosis of sarcomatoid carcinoma, possibly derived from cholangiocarcinoma. Despite aggressive treatment, the patient died on 39th day after the surgery due to cancerous pleuritis and multiple bone metastases. The development of sarcomatoid carcinoma of the liver is reportedly associated with prior treatments such as transarterial chemoembolization, while the present patient had no history of anticancer therapy. This very rare case with some bibliographical comments is presented.