A semiconductor device including a chip package, a dielectric structure and a first antenna pattern is provided. The dielectric structure disposed on the chip package and includes a cavity and a vent in communication with the cavity. The first antenna pattern disposed on the dielectric structure, wherein the chip package is electrically coupled to the first antenna pattern, and the cavity of the dielectric structure is disposed between the chip package and the first antenna pattern. A manufacturing method of a semiconductor device is also provided.