A semiconductor device package includes a substrate and an antenna module. The substrate has a first surface and a second surface opposite to the first surface. The antenna module is disposed on the first surface of the substrate with a gap. The antenna module has a support and an antenna layer. The support has a first surface facing away from the substrate and a second surface facing the substrate. The antenna layer is disposed on the first surface of the support. The antenna layer has a first antenna pattern and a first dielectric layer.