A multilayer wiring board assembly component comprises: an insulating substrate component (the insulating resin layer 111); a conductive layer 112 formed on one surface of said insulating substrate component 111 in the form of an electrode pattern; an adhesive layer 113 formed on the other surface of said insulating substrate component 111; and a conductive resin composition 115 with which is filled a through hole passing through said insulating substrate component 111, said adhesive layer and said conductive layer in order to make interlayer interconnection. The bore diameter of the conductive layer portion 114b of the through hole 114 is smaller than the bore diameter of the insulating resin layer portion and the adhesive layer portion 114a to establish electrical connection between the conductive resin composition 115 and the conductive layer 112 by the rare surface 112a of the conductive layer 112.