A wiring board for mounting a semiconductor element or electronic component having a plurality of wiring layers, an insulating layer provided between these wiring layers, and a via which is provided to the insulating layer and which electrically connects the wiring layers. In this wiring board, the cross-sectional shape of the via in the plane parallel to the wiring layers is obtained by the partial overlapping of a plurality of similar shapes (circles). Stable operation can be obtained in a semiconductor element by minimizing obstacles to increased density, effectively increasing the cross-sectional area of the via, and preventing the wiring resistance from increasing by making the cross-sectional shape of the via into a shape obtained by the partial overlapping of a plurality of similar shapes.