A semiconductor device and a fabrication method thereof are provided. A semiconductor device which is packaged as it includes a semiconductor in which an electronic circuit is disposed, the semiconductor device including: a substrate; a semiconductor chip which has a semiconductor main body having the electronic circuit formed thereon, a pad electrode formed on the semiconductor main body and a projected electrode that is connected to the pad electrode and projected from a surface of the semiconductor main body, wherein the semiconductor chip is mounted on the substrate from the back side of the surface to form the projected electrode thereon; and an insulating layer which is formed as the semiconductor chip buried therein and is polished from a top surface of the insulating layer to a height at which a top of the projected electrode is exposed.