According to one embodiment, a semiconductor device includes a circuit substrate, a semiconductor element, a sealing resin layer, and a conductive shielding layer. The circuit substrate includes an insulating layer, a plurality of interconnections forming first interconnection layers provided on an upper surface side of the insulating layer, a plurality of interconnections forming second interconnection layers provided on a lower surface side of the insulating layer, and a plurality of vias penetrating from the upper surface to the lower surface of the insulating layer. The semiconductor element is mounted on the upper surface side of the circuit substrate. The conductive shielding layer covers the sealing resin layer and part of an end portion of the circuit substrate. Any of the plurality of vias and the conductive shielding layer are electrically connected.