To solve the problem of a prior art that loss of a high frequency signal through a conductor pattern is increased in a prior art multi-piece wiring board when the position of a dividing groove is shifted.

In a multi-piece wiring board, wherein substantially square wiring board regions defined with dividing grooves 6 are arranged longitudinally and laterally on the main surface of a mother board, and there is provided a wiring pattern 2 among a plurality of insulating layers 1a to 1c so as to stride the dividing groove 6 between adjacent wiring board regions or among the insulating layers 1a to 1c and on the principal surface of the mother board, and further there is provided a through-hole 7' which strides the dividing groove 6 and passes through the wiring pattern 2, the through-hole 7 consists of a first through-hole 7b' where the wiring pattern 2 is made a ground wiring G on opposite sides of the wiring board regions, and of a second through-hole 7a' made a signal wiring S on one hand, and made the ground wiring G on the other hand. The first through-hole 7b' includes a conductor formed on the entire of an internal peripheral surface, while the second through-hole 7a' includes a conductor formed on an internal peripheral surface only of an insulating layer located between the signal wiring S and the ground wiring G.