Abstract: Disclosed is a breeding nuclear fuel mixture including metallic thorium useable in a nuclear power plant, prepared by mixing uranium dioxide (UO2) or plutonium dioxide (PuO2) having ceramic properties with metallic thorium (Th), in order to enable thorium breeding by neutrons released during nuclear fission of U or Pu and conversion of the bred thorium into a novel nuclear fissile material, i.e., U-233, thereby ensuring continuous nuclear fission. The foregoing nuclear fuel mixture may be burned at a reactor core of a nuclear power plant through thorium breeding over a long period of time. Therefore, when the inventive breeding nuclear fuel mixture is employed in a nuclear power plant, utilization of the nuclear power plant may be increased while maximizing conservation of limited uranium resources.