A 56-year-old man presented to our hospital complaining of right upper quadrant pain. An abdominal dynamic CT scan revealed a tumor in the right liver lobe measuring 84 mm in diameter and right portal vein branch thrombosis. AFP and PIVKA-II levels were also high, and the patient was diagnosed with hepatocellular carcinoma. Sorafenib treatment was started because Vp3 portal vein tumor thrombosis was associated. CT scan conducted 5 months after the initiation of sorafenib treatment showed that the tumor markedly shrank to 50 mm in diameter with no arterial enhancement, and portal vein thrombosis also shrank. Due to severe diarrhea, it became difficult to continue administration of sorafenib, and the patient was scheduled to receive right liver lobectomy and removal of the portal vein thrombosis. Intraoperative findings disclosed absence of the thrombosis so that only right liver lobectomy was performed. Pathological findings showed that the tumor cells in the main tumor and the peripheral portal vein were necrotic, and no viable tumor cells were observed. The patient is currently alive without recurrence as of 27 months after the surgery.