A semiconductor element mounted on an insulating resin layer formed on a wiring layer is sealed by a sealing resin. On the wiring layer, a protruding electrode protruding to the side of the semiconductor element and a protruding section are integrally formed with the wiring layer, respectively. The protruding electrode is electrically connected to an element electrode of the semiconductor element by penetrating the insulating resin layer. The protruding section is arranged to surround the semiconductor element along the four sides of the semiconductor element, and is embedded in the sealing resin up to a position above a section where the protruding electrode and the element electrode are bonded.