A semiconductor device package includes a substrate, a package body, a conductive layer, a dielectric layer, a magnetic layer, a first insulating layer and a coil. The package body is disposed on the substrate. The package body has a first part and a second part disposed above the first part. The conductive layer is disposed on the first part of the package body and is electrically connected to the substrate. The dielectric layer is disposed on the conductive layer. The magnetic layer is disposed on the dielectric layer. The first insulating layer is disposed on the magnetic layer. The coil is disposed on the first insulating layer. The coil has a first terminal electrically connected with the magnetic layer.