A spread illuminating apparatus includes a light converging element which has a refractive index profile in a direction orthogonal to two major surfaces of a light conductive plate, and which is disposed between at least one light source and one end surface of the light conductive plate. The light converging element comprises: a plurality of transparent resin films which have respective refractive indexes so as to constitute a refractive index gradation mirror-imaged with respect to the center plane of the light converging element, and which are layered over one another; and a plurality of light-transmittable adhesive layers each of which is sandwiched between two adjacent transparent resin films.