It is possible to provide a semiconductor device which can be obtained at a high reliability by warping an insulating substrate stably into a convex shape while ensuring a close contact between a cooling member and the insulating substrate. The semiconductor device includes an insulating substrate, a semiconductor element disposed on a first surface of the insulating substrate, a case connected to the insulating substrate, and a resin filled inside the case. Assuming that the thickness of the insulating substrate is denoted by t1, the thickness of the resin is denoted by t2, the linear expansion coefficient of the insulating substrate is denoted by α1, and the linear expansion coefficient of the resin is denoted by α2, the relationship therebetween satisfies t2≧t1 and α2≧α1, and a second surface of the insulating substrate opposite to the first surface thereof is warped into a convex shape.