A superconductor includes an oxide of HgA n +₃Cu n +₂O 2n+6+x , where "A" denotes alkaline earth element and "n" denotes an integer equal to or greater than 0, and "x" denotes a value in a range as -1 n+3 Cu n +₂O 2n+6 . The perovskite layer includes two layers of CuO₅ pyramids which are opposite to each other, "n" CuO₂ layers extending between the two pyramid layers, and 1-atom layers of the alkaline earth element A.