The present invention provides an antitumor drug comprising a tegafur gimeracil oteracil potassium-containing agent, characterized in that said antitumor drug is repeatedly dosed once a day on alternate days for 4 days per week in a dosage, in terms of the amount of tegafur, of at least 80 mg per dosing in the case where the body surface area of a patient to be dosed is less than 1.25 m2, at least 100 mg per dosing in the case where the body surface area thereof is 1.25-1.5 m2, or at least 120 mg per dosing in the case where the body surface area thereof is 1.5 m2 or greater.
