PURPOSE: To simplify a complicated circuit structure constructed by conventional bus bars and incorporate a number of circuits at a small space without being restricted by generation of heat, by forming the circuits of a wiring board with superconducting materials.

CONSTITUTION: Superconductive paste material is used and a desired pattern is made by screen printing on both sides of a heat-resisting insulating plate 10 made of an inorganic ceramic and so on and then, the circuit 11 is obtained by baking its plate at a high temperature. At a place where both sides of the circuit 11 are connected, a hole 10a is made in the insulation plate 10 and the superconductive paste is coated inside the hole in the same way as mentioned above. Thus, a connecting path 11' is formed by baking its hole.