A novel pharmaceutical composition for treating or preventing hepatocellular carcinoma and a method of treatment are provided. A pharmaceutical composition for treating or preventing liver cancer is obtained by combining a chemotherapeutic agent with an anti-glypican 3 antibody. Also disclosed is a pharmaceutical composition for treating or preventing liver cancer which comprises as an active ingredient an anti-glypican 3 antibody for use in combination with a chemotherapeutic agent, or which comprises as an active ingredient a chemotherapeutic agent for use in combination with an anti-glypican 3 antibody. Using the chemotherapeutic agent and the anti-glypican 3 antibody in combination yields better therapeutic effects than using the chemotherapeutic agent alone, and mitigates side effects that arise from liver cancer treatment with the chemotherapeutic agent.