A semiconductor device and a production method thereof capable of reducing warps of a semiconductor wafer when packaging at a wafer level in a SiP type semiconductor device, is configured that an insulating layer is formed by stacking a plurality of resin layers on a semiconductor chip formed with an electronic circuit, wiring layers are buried in the insulating layer and electrically connected to electrodes, and formation areas of the plurality of resin layers become gradually smaller from an area of an upper surface of the semiconductor chip as they get farther from the semiconductor chip, so that a side surface and an upper surface of each of the resin layers and the upper surface of the semiconductor chip form a stepwise shape.