A spread illuminating apparatus includes: a point light source; a light conductor plate having a prism array formed at a side surface thereof at which the point light source is disposed; a frame which houses the point light source and the light conductor plate and which includes an elastically active area to urge the light conductor plate toward the point light source; and a heat-resistant transparent spacer which is composed of an elastic layer preferably made of heat resistant silicone rubber and a non-elastic layer made of polyethylene terephthalate and which is disposed between the point light source and the prism array of the light conductor plate such that the elastic layer makes contact with the point light source and the non-elastic layer makes contact with the prism array.