A light guide plate has a light guide plate member having a light incident surface on an end face of the light guide member, and a light emitting surface on a front surface of the light guide plate member, wherein the light incident surface is structured to have light incident thereon, and wherein the light emitting surface is structured to widen and emit light incident thereon out of the light guide plate member, and a directivity changing unit arranged on a light incident end portion of the light guide plate member on the front surface or a back surface of the light guide plate member. The directivity changing unit has a first inner inclined surface and a second inner inclined surface that change a directivity of the incident light within the directivity changing unit to widen the light laterally with respect to a direction perpendicular to the light incident surface.