The present invention relates to a pharmaceutical composition for preventing or treating Gleevec-resistant leukemia, containing, as an active ingredient, ginsenoside F1 or Rg3 which exhibits a preventive or therapeutic effect on Gleevec-resistant leukemia through enhancing cell killing activity of NK cells; a method for treating Gleevec-resistant leukemia comprising a step of administering the pharmaceutical composition; and a food composition for preventing or ameliorating Gleevec-resistant leukemia. Since the pharmaceutical composition of the present invention can effectively treat leukemia that exhibits resistance to conventional Gleevec, the pharmaceutical composition can be widely used for effective leukemia treatment.