To prevent wire breaking between a through conductor, which electrically connects the wiring conductor layers of a wiring board with each other, and the wiring conductor layer.

This is a wiring board 6 which comprises an insulating substrate 1, a plurality of insulating layers 2 formed on the insulating substrate 1, wiring conductor layers 3 formed on each surface of the insulating substrate 1 and the plural insulating layers 2, and a through-hole 5 constituted of a conductor filled in the through-hole 4 bored from each surface of the plural insulating layer 2 to the rear and electrically connecting the wiring conductor layers 3 with one another. A stacked through- conductor part 10 is formed by arranging the conductor filled in the through-hole 4 of each insulating layer 2 in vertical direction, and also embedding the end on the rear side of the insulating layer 2 of each conductor to a depth of one-tenth to half the thickness of the wiring conductor layer in the wiring conductor layer 3 on the rear side of the insulating layer 2 on each conductor. This board can be made into a wiring board, which is high in reliability for connection without the occurrence of wire breaking, since the end on the rear side of the insulating layer 2 on each conductor is embedded in the wiring conductor layer 3 on the rear side of each insulating layer 2.