Patent ID: 7481568

Claim:
A surface light source device comprising: a tubular light source; a holder that is attached to at least one end portion of the light source and has at least one side surface; and a flat plate type light guide body that has one end portion brought into contact with one side surface of the holder and guides light incident from the one end portion to one principal surface in a planar form, the light source and the holder being detachably attached in a state that the one end portion of the light guide body faces the light source, wherein the holder has a shape of the one side surface of the holder designed as an uneven surface so that the contact area between the one side surface of the holder and the one end portion of the light guide body is reduced, the light source and the holder are detachable from the light guide body, and the uneven surface is provided with a plurality of projecting portions arranged in a direction crossing the detaching direction of the light source and the holder with respect to the light guide body, and large-diameter projecting portions provided at both the sides of the uneven surface so as to sandwich the plurality of projecting portions therebetween, the lateral dimension of the large-diameter projecting portions being larger than that of the projecting portions.