Providing a novel combination therapy of FTD / TPI combination drug that exhibits remarkable antitumor effects and has few side effects. An antitumor agent wherein an FTD / TPI combination agent is administered in an amount of 35 to 70 mg / m 2 / day in an amount equivalent to FTD, and CPT-11 is administered in an amount of 45 to 144 mg / m 2 / day.顕著な抗腫瘍効果を示し、副作用の少ないFTD・TPI配合剤の新規な併用療法の提供。 FTD・TPI配合剤がFTD換算量で35~70mg/m2/day投与され、CPT-11が45~144mg/m2/day投与されることを特徴とする抗腫瘍剤。