A support block has a first face, a second face opposed to the first face, and first and second through holes communicating between the first face and the second face, and is formed with resin material. The first face, the second face, and the first and second through holes are covered with an electrically conductive plated coating. First and second probes are electrically connected to terminals of a device to be tested provided on a side of the first face and to terminals connected to a testing apparatus provided on a side of the second face. The first probe is provided in the first through hole and is electrically connected to the plated coating on the first through hole, the second probe is provided in the second through hole and is electrically connected to the plated coating on the second through hole. A pattern for defining a first region electrically connected to the first probe via the plated coating and a second region electrically connected to the second probe via the plated coating is formed by partially removing the plated coating on the first face and the second face, where the second region is electrically isolated from the first region. Electrodes of an electronic component are respectively connected to the first and second regions.