There is here disclosed a semiconductor device comprising a first base material which is provided at least one semiconductor device mounted on one main surface, a plurality of first connection portions provided on the main surface and being electrically connected to the semiconductor device, and a plurality of second connection portions provided outside a region on which the semiconductor device is mounted on the main surface, and a second base material which is disposed facing other main surface of the first base material on a side opposite to the side on which the semiconductor device is mounted, bonded to an edge of the first base material, and provided a plurality of third connection portions provided outside a region on which the first base material is mounted on and being electrically connected to at least one of the second connection portions.