An advantage of the present invention is to suppress moisture infiltrating from a pad electrode portion from spreading over the surface of a wiring pattern and improve the reliability of a packaging board. The wiring pattern of the packaging board is formed on an insulating substrate and includes a wiring region, an electrode region (pad electrode) connected with a semiconductor device, and a boundary region provided between the wiring region and the electrode region. A gold plating layer is provided on the surface of the electrode region of the wiring pattern. The top surface of the boundary region of the wiring pattern is so formed as to be dented from the top surface of the wiring region of the wiring pattern, and there is provided a stepped portion in the boundary region. A solder resist is formed in such a manner as to cover part of the gold plating layer and the wiring pattern corresponding to the boundary region and the wiring region, and the solder resist has a predetermined opening through which to connect to the semiconductor device. A conductive member is connected to the gold plating layer in the electrode region, and a molded resin layer seals the entire semiconductor module.