Disclosed are a sensitizing composition for thermal cancer therapy using electromagnetic waves and a method of treating cancer using the same, wherein the sensitizing composition increases sensitivity upon treatment of cancer using electromagnetic waves, and includes a metal ion, a metal ion-bound material, "metal ion-noncovalently bound apotransferrin" (transferrin), or a metal ion-noncovalently bound apotransferrin derivative. The sensitizing composition that targets cancer enables selective delivery of the metal ion to tumorous tissue when administered in vivo, and thus the generation of heat in tumorous tissue in which the metal ion accumulates is increased upon thermal cancer therapy using electromagnetic waves, thereby maximizing the efficacy of the thermal cancer therapy using electromagnetic waves in treating cancer. Further, this thermal therapy using the sensitizing composition is effective at treating cancer without pain or side effects and is thus expected to be widely useful in anticancer treatment, and can also be used in combination with chemotherapy, radiation therapy, etc., ultimately increasing the potential to cure cancer.
