A semiconductor device designed to reduce the warp of a substrate due to curing contraction, etc. of an insulation pattern while forming the insulation pattern on the surface of a substrate so that it may be interposed between a semiconductor chip and a conductor pattern by offering a semiconductor chip mounting substrate equipped with a flexible substrate 11 (insulating film 16) having a chip mounting region 19 for mounting a semiconductor chip 13 via an adhesive 12, conductor patterns 20 that are formed on the surface of the above-mentioned substrate 11 and electrically connected to the semiconductor chip 13 in an external region of the above-mentioned chip mounting region 19, and an insulation pattern 21 formed on the surface of the substrate 11 and partially in the chip mounting region 19 so that it may be interposed between the semiconductor chip 13 and the conductor patterns 20.