as to provide a reflecting surface which reflects light toward the front side the pattern of the concave dots 17 varies successively from rough to fine moving away from the vicinity of the light source accommodating recess 16 of the light directing plate 15 so as to equalize the quantity of light reflected by the concave dots 17 within the light source accommodating recess 16 the light sources l are arranged so that respective light emitting portions of the light sources l face the whole of the reflecting surface composed of the concave dots 17 formed in the rear surfaces of the light directing plate 15 the light sources l used in this embodiment may be so called linear light sources such as xenon lamps constituted with linear filaments two such linear light source l aligned in the widthwise direction of the light directing plate 15 of relatively great width may suffice for the light directing plate 15 so that illuminating losses can be made small reference numeral 18 designates an inner lens additionally provided in front of the above mentioned light directing plate 15 at a position in opposition to the front panel 6 and with a certain interval therebetween the inner lens 18 is formed by molding transparent synthetic resin such as acrylic resin in such a manner that as shown in fig8 a plurality of sawtooth step structures.