The invention is directed to enhancement of performance of a back surface incident type semiconductor device having a light receiving element and a manufacturing method thereof without increasing a manufacturing cost. A supporting body is attached to a front surface of a semiconductor substrate formed with a light receiving element and its pad electrode. Then, the supporting body is etched to form a via hole penetrating the supporting body and exposing the pad electrode. Then, a wiring connected to the pad electrode and extending onto a front surface of the supporting body through the via hole is formed. Lastly, the semiconductor substrate is separated into a plurality of semiconductor dies by dicing. The semiconductor device is mounted so that the supporting body faces a circuit board.