Abstract: The present invention makes it possible to fix connector pins at low cost. Connector pins penetrate both a holding substrate and a main substrate. The connecter pins can be restrained from an outward radial direction by both wall surfaces of pin holes of the holding substrate, and wall surfaces of through-holes of the main substrate, thus improving upright-standability of the connector pins. The holding substrate is formed of a same raw substrate as the main substrate is formed of, and permanent resists which are laminated on the holding substrate, and ink used for silk screen printing to which the holding substrate is subjected, are made of a same material of the main substrate, so that fire resistance of the holding substrate and fire resistance of the main substrate are same. Therefore, if the main substrate clears a predetermined fire-resistance standard, the holding substrate also inevitably clears the predetermined fire-resistance standard.