An illumination display panel that forms part of a housing and has a display portion for illuminated display comprises a resin panel having a first molded portion made of an opaque resin at a portion excluding the display portion, and a second molded portion disposed on the back surface side of the first molded portion and made of a light-transmitting resin having a protrusion where the first molded portion is not present. The protrusion is fitted to the first molded portion. A light source mounting substrate is disposed on the back surface side of the resin panel. At least a light source of the light source mounting substrate is sealed by the second molded portion. An integrally molded product of the light source mounting substrate and the second molded portion is filled and solidified at a low pressure while compressing a cavity of a molding mold.