There is disclosed a semiconductor device comprising at least two substrates, at least one wiring being provided in each of the substrates, the substrates being stacked such that major surfaces on one side of each thereof oppose each other and the wirings being connected between the major surfaces, and a plurality of connecting portions being provided adjacent to each other while connected to each wiring on the major surfaces opposing each other, at least one of the connecting portions provided on the same major surface being formed smaller than the adjacent other connecting portion, the connecting portions being provided at positions opposing each other one to one on the major surface, the connecting portions being connected so that the wirings are connected between the major surfaces, one connecting portion of a pair of the connecting portions connected one to one being formed smaller than the other connecting portion.