LIGHT GUIDE BODY AND SURFACE LIGHT SOURCE DEVICE

PROBLEM TO BE SOLVED: To provide a light guide body capable of making easy an application of local dimming in a surface light source device of an edge-light type.SOLUTION: A light guide body of an edge-light type surface light source device includes a light incident edge face 31, a light emission face 33 which crosses almost orthogonally the light incident edge face and is located on the opposite side, and a rear face 34. At least either on the light emission face 33 or the rear face 34, there is provided a directional light emitting function part made of a lens row forming face where lens rows 33' are formed in parallel. The lens row 33' extends in a direction almost orthogonally crossing the light incident edge face 31 and has a shape in which the cross-section parallel to the light incident edge face 31 is a convex-curved line or has a shape in which a straight line is combined to both ends of the convex-curved line. When the pitch of the lens rows 33' is made P and the height h, a relational formula of 0.4×P≤h is satisfied.