A stress mitigation region is formed in which a predetermined number of stress mitigation holes penetrating through a wiring are disposed is formed in a proximity of a bonding portion of an electronic component via which the electronic component is bonded to the wiring with an electrically conductive bonding agent. Accordingly, even if a stress is generated in the wiring due to a heat, the stress mitigation holes are deformed so that the stress acted upon the electrically conductive bonding agent becomes small and a generation of cracks in the electrically conductive bonding agent can be suppressed. In addition, the stress mitigation holes are made circular so that concentrations of a current and the stress can be reduced and the generation of the cracks in the wiring can be suppressed.