A light conducting body has a generally conical through bore defined therein. The conical through bore includes a front bore part defined by a sloped surface and a rear bore part defined by a concave surface. A light conducting dial board is installed in the conical through bore with its front face facing forward and positioned in the vicinity of the junction portion between the front and rear bore parts. The dial board has a peripheral edge separated from the inner wall surface of the conical through bore thereby to define therebetween a circumferentially extending space. A light conducting supporting plate is attached to a rear surface of the dial board. The supporting plate is formed with a light transmitting portion which extends rearward and has an rear end intimately received in a recess formed in the rear end of the light conducting body. A plurality of light sources are positioned behind the rear end of the light conducting body. A first light introducing structure is defined by the rear end of the light conducting body, from which light from the light sources enters the light conducting body and travels toward the sloped and concave surfaces of the front and rear bore parts to illuminate the same from within. A second light introducing structure is defined by the light conducting supporting plate, through which light from the light sources enters the light conducting supporting plate and travels toward the dial board to illuminate the same from within.