In a semiconductor device in which a copper plating layer is used for a conductor of an antenna and in which an integrated circuit and the antenna are formed over the same substrate, an object is to prevent an adverse effect on electrical characteristics of a circuit element due to diffusion of copper, as well as to provide a copper plating layer with favorable adhesiveness. Another object is to prevent a defect in the semiconductor device that stems from poor connection between the antenna and the integrated circuit, in the semiconductor device in which the integrated circuit and the antenna are formed over the same substrate. In the semiconductor device, a copper plating layer is used for the antenna, an alloy of Ag, Pd, and Cu is used for a seed layer thereof, and TiN or Ti is used for a barrier layer.