In order to improve reliability of a semiconductor device, the semiconductor device includes a semiconductor chip, a die pad, a plurality of leads, and a sealing portion. The die pad and the leads are made of a metal material mainly containing copper. A plating layer is formed on a top surface of the die pad. The plating layer is formed by a silver plating layer, a gold plating layer, or a platinum plating layer. The semiconductor chip is mounted on the plating layer on the top surface of the die pad via a bonding material. The plating layer is covered by the bonding material not to be in contact with the sealing portion.