A semiconductor device is provided comprising a support, an adhesive resin layer, an insulating layer, a redistribution layer, a chip layer, and a mold resin layer. The adhesive resin layer consists of a resin layer (A) comprising a photo-decomposable resin containing a fused ring in its main chain and a resin layer (B) comprising a non-silicone base thermoplastic resin and having a storage elastic modulus E′ of 1-500 MPa at 25° C. and a tensile break strength of 5-50 MPa. The semiconductor device is easy to fabricate and has thermal process resistance, the support is easily separated, and a semiconductor package is efficiently produced.