A semiconductor device includes a conductive shield layer that has a first portion covering a surface of a sealing resin layer and a second portion covering side surfaces of the sealing resin layer and side surfaces of the substrate. Portions of wiring layers, including a grounding wire, on or in the substrate have cut planes which are exposed to the side surfaces of the substrate and spread out in a thickness direction of the substrate. A cut plane of the grounding wire is electrically connected to the shield layer. An area of the cut plane of the grounding wire is larger than an area of a cross section of the grounding wire parallel to, and inward of the substrate from, the cut plane of the grounding wire.