Abstract: A Mg-doped high-temperature superconductor having low superconducting anisotropy includes a two-dimensional layered structure constituted by a charge reservoir layer and a superconducting layer, wherein some or all atoms constituting the charge reservoir layer are Cu and O atoms, metallizing or rendering the charge reservoir layer superconducting, a portion of the Ca of the CunCan-1O2n constituting the superconducting layer is replaced by Mg, increasing superconductive coupling between CuO2 layers, a thickness of the superconducting layer is increased, and therefore coherence length in a thickness direction is increased based on the uncertainty principle, lowering superconducting anisotropy.