Even when a stiffener is omitted, the semiconductor device which can prevent the generation of twist and distortion of a wiring substrate is obtained. As for a semiconductor device which has a wiring substrate, a semiconductor chip by which the flip chip bond was made to the wiring substrate, and a heat spreader adhered to the back surface of the semiconductor chip, and which omitted the stiffener for reinforcing a wiring substrate and maintaining the surface smoothness of a heat spreader, a wiring substrate has a plurality of insulating substrates in which a through hole whose diameter differs, respectively was formed, and each insulating substrate contains a glass cloth.