PURPOSE: To prevent a high frequency electromagnetic radiation from being generated in a power supply and a grounded circuit by arranging a ground pattern on one of high dielectric constant substance layers on a board and arranging a power supply pattern and a signal line pattern on the other of the high dielectric constant substance layers on the board.

CONSTITUTION: A high dielectric constant substance layer 12 is printed in a range a little wider than the region of a ground pattern on one surface of a board 10. Similarly, a high dielectric constant substance layer 11 is printed in the range opposite to the high dielectric constant substance layer 12 on the other surface of the board 10. In this case, for example, polyethylene, polystyrene, polycarbonate or the like is used as the high dielectric constant substance. Thereafter, a copper plating is applied to both surfaces of the board 10, a photoresist material for the ground pattern and a signal line pattern is coated on the rear of the two-layer printed board 10 and the photoresist material for a power supply pattern and the signal line pattern is applied to the surface of the two-layer printed board 10. Then, copper on which the photoresist is not coated on both surfaces of the two-layer printed board is removed by etching. Subsequently, when the photoresist is removed, the power supply pattern 13, the ground pattern 14 and the signal line patterns 15 and 16 are formed.