Wiring substrate and semiconductor device

A wiring substrate includes first wiring portions, an insulation layer covering the first wiring portions, openings extending through the insulation layer in a thickness-wise direction, partially exposing upper surfaces of the first wiring portions, and differing from each other in capacity, and second wiring portions, each of which includes a via wiring filling one of the openings and a columnar connection terminal electrically connected to the via wiring and arranged on an upper surface of the insulation layer. The via wiring includes an electrolytic plated layer and an electroless plating structure including N layers (N is integer and ≥0) arranged between the electrolytic plated layer and the upper surface of the first wiring portion exposed in a bottom of the opening. The via wiring is formed so that the electroless plating structure has a thickness that increases as a capacity of the opening filled with the via wiring is increased.