Disclosed is an antitumor agent or postoperative adjuvant chemotherapeutic agent for a hepatocellular carcinoma patient who underwent transarterial embolization.Specifically disclosed is an antitumor agent or a postoperative adjuvant chemotherapeutic agent, which contains TSU-68 or a salt thereof and can be administered to a hepatocellular carcinoma patient, who has undergone transarterial embolization, within two weeks after the operation.