PURPOSE: To enhance reliability of a through hole with fine diameter by embed ding a conductive paste material and by performing etching while exposing a sensitive etching resist to circuits including a through hole after forming a conductor on the entire surface of a board.

CONSTITUTION: Drilling machining is performed to a substrate 1, chemical plating is performed to the inner wall of a hole part 4 and the entire front and rear surfaces of the board 1, and then an electrical plating layer 8 is formed. Then, areas other than the circuit part are covered by an insulation film 9 and a conductive paste material is embedded into the hole part 4. The paste is an ink consisting of a mixture of calcium carbonate, nitric acid, barium carbonate, magnesium carbonate, or zinc oxide as well as carbon powder and metal powder. Then, it is dipped into an electrodeposition liquid to form an etching resist 10. Then, ultraviolet rays 5a are irradiated to allow etching resist to be cured. The insulation film 9 and the conductor part 8 are eliminated. Furthermore, an etching resist 10 and a conductive paste 11 at the circuit part are eliminated to complete formation of circuit pattern.