The present invention provides an antitumor agent or postoperative adjuvant chemotherapeutic agent for a hepatocellular carcinoma patient who has been treated by transarterial embolization. An antitumor agent or postoperative adjuvant chemotherapeutic agent comprising TSU-68 or a salt thereof, which can be administered to a hepatocellular carcinoma patient within 2 weeks after transarterial embolization, is provided.本發明提供一種針對經實施肝動脈栓塞手術之肝細胞癌患者之抗腫瘤劑或手術後輔助化學療法劑。本發明之抗腫瘤劑或手術後輔助化學療法劑含有可對經實施肝動脈栓塞手術之肝細胞癌患者於實施手術後兩週以內投予之TSU-68或其鹽。