Surface light source device

Patent Granted A dichroic filter column (4) is provided on an incident surface (11). At least one of two end parts of a light guide plate (1) in a thickness direction is divided into a plurality of light guide paths (6), in a width direction of the light guide plate (1) by a plurality of cutout grooves (5). Portions of the plurality of light guide paths (6) on an incident surface (11) side are aligned in accordance with positions of a plurality of dichroic filters (31), respectively. The plurality of dichroic filters (31) are elements of the dichroic filter column (4).