A planar light-emitting device includes a lightguide plate (7), a light source including at least one light-emitting package (6) that makes light enter the lightguide plate, and a reflecting sheet (10, 11) that returns light leaking from the light source. The lightguide plate has an upper surface as a light exit surface, a lower surface opposite to the upper surface, and a peripheral edge surface a part of which is disposed as a light entrance surface (7'). The light source includes at least one light-emitting package (6) having a substrate, at least one light-emitting element mounted on a mount surface of the substrate, and a light-transmitting resin provided on the mount surface to seal the light-emitting element. The reflecting sheet is disposed to face at least one of the upper and lower surfaces of the lightguide plate and to extend beyond the light entrance surface as far as over or underneath the light-transmitting resin.