A backlight unit comprising: a plurality of light sources adapted to radiate light; and light guide panel adapted to guide light radiated from the plurality of ight sources, the light guide panel comprising: an incidence surface suitable for arrangement to face a plurality of light sources separated apart by a predetermined distance; at least one dark portion reducing unit formed on the incidence surface between the locations for adjacent pairs of the light sources without facing the light sources and at the edges at both ends of the incidence surface, and arranged to reflect the light incident from the light sources to reduce the creation of a dark portion; an upper surface arranged to transmit a portion of incident light and to reflect the rest of the incident light; and a lower surface arranged to face the upper surface and to reflect the light incident from the incidence surfaces and the at least one dark portion reducing units, wherein the at least one dark portion reducing unit is formed of a groove that is oblique from the incidence surface toward the lower surface and of increasing width in a direction from the upper surface towards the lower surface, and further formed through the incidence surface and the lower surface, wherein each of the dark portion reducing units reflects light, having passed through the incidence surface between the dark portion reducing units and entered the light guide panel, to the upper surface thereof and supplies light to the regions above the dark portion reducing units. a plurality of light sources adapted to radiate light; and light guide panel adapted to guide light radiated from the plurality of ight sources, the light guide panel comprising: an incidence surface suitable for arrangement to face a plurality of light sources separated apart by a predetermined distance; at least one dark portion reducing unit formed on the incidence surface between the locations for adjacent pairs of the light sources without facing the light sources and at the edges at both ends of the incidence surface, and arranged to reflect the light incident from the light sources to reduce the creation of a dark portion; an upper surface arranged to transmit a portion of incident light and to reflect the rest of the incident light; and a lower surface arranged to face the upper surface and to reflect the light incident from the incidence surfaces and the at least one dark portion reducing units, wherein the at least one dark portion reducing unit is formed of a groove that is oblique from the incidence surface toward the lower surface and of increasing width in a direction from the upper surface towards the lower surface, and further formed through the incidence surface and the lower surface, wherein each of the dark portion reducing units reflects light, having passed through the incidence surface between the dark portion reducing units and entered the light guide panel, to the upper surface thereof and supplies light to the regions above the dark portion reducing units. an incidence surface suitable for arrangement to face a plurality of light sources separated apart by a predetermined distance; at least one dark portion reducing unit formed on the incidence surface between the locations for adjacent pairs of the light sources without facing the light sources and at the edges at both ends of the incidence surface, and arranged to reflect the light incident from the light sources to reduce the creation of a dark portion; an upper surface arranged to transmit a portion of incident light and to reflect the rest of the incident light; and a lower surface arranged to face the upper surface and to reflect the light incident from the incidence surfaces and the at least one dark portion reducing units, wherein the at least one dark portion reducing unit is formed of a groove that is oblique from the incidence surface toward the lower surface and of increasing width in a direction from the upper surface towards the lower surface, and further formed through the incidence surface and the lower surface, wherein each of the dark portion reducing units reflects light, having passed through the incidence surface between the dark portion reducing units and entered the light guide panel, to the upper surface thereof and supplies light to the regions above the dark portion reducing units.