The present invention employs a configuration described as follows, so as to realize a surface light source apparatus which attain a thinness and a further improved luminance uniformity without suffering a deterioration in luminance. Specifically, space maintaining sections (6) are provided on a substrate (4) onto which light sources (2) are mounted, so as to cause an optical sheet (5) and a light emitting surface made up of outputting surfaces (1c) to be away from each other by a given distance. The space marinating sections 6 are provided so as to protrude from respective gaps each of which occurs between adjacent two of light guides (1) which are juxtaposed so as not to overlap each other.