It is intended to reduce the price of a semiconductor device and increase the reliability thereof. In an interposer, a plurality of wiring layers are disposed between uppermost-layer wiring and lowermost-layer wiring. For example, a third wiring layer is electrically coupled directly to a first wiring layer as the uppermost-layer wiring by a long via wire extending through insulating layers without intervention of a second wiring layer. For example, an upper-surface terminal made of the first wiring layer is electrically coupled directly to a via land made of the third wiring layer by the long via wire. Between the adjacent long via wires, three lead-out wires made of the second wiring layer can be placed. The number of the lead-out wires that can be placed between the adjacent long via wires is larger than the number of the lead-out wires that can be placed between the adjacent via lands.