A backlight unit comprising: a light supply unit, a panel guide mold and a bottom cover, the light supply unit being disposed between the panel guide mold and the bottom cover, wherein the panel guide mold is coupled with a top surface of the light supply unit and comprises a plurality of first mold units spaced apart from each other and a plurality of second mold units, wherein each one of the plurality of second mold units is disposed between two consecutive first mold units, and wherein the plurality of first mold units are offset in an outward direction relative to side surfaces of the plurality of second mold units to form an alternating, step-like structure, the outward direction being perpendicular to the side surfaces of the plurality of second mold units and being parallel to the top surface of the light supply unit and wherein the bottom cover is coupled with the panel guide mold and supports the light supply unit, and comprises a plurality of first sidewalls spaced apart from each other and a plurality of second sidewalls, wherein each one of the second sidewalls is disposed between two consecutive first sidewalls, and wherein each of the plurality of the first sidewalls is inserted and coupled to a corresponding one of the plurality of first mold units and each of the plurality of second sidewalls receives and is coupled to a corresponding one of the plurality of second mold units, such that where each first mold unit protrudes outward from the side surfaces of the plurality of second mold units, a corresponding first sidewall is recessed inward relative to the side surfaces of the plurality of second side walls and where each second sidewall protrudes outward relative to the side surfaces of the plurality of first sidewalls, a corresponding second mold unit is recessed inward from the side surfaces of the plurality of first mold units. a light supply unit, a panel guide mold and a bottom cover, the light supply unit being disposed between the panel guide mold and the bottom cover, wherein the panel guide mold is coupled with a top surface of the light supply unit and comprises a plurality of first mold units spaced apart from each other and a plurality of second mold units, wherein each one of the plurality of second mold units is disposed between two consecutive first mold units, and wherein the plurality of first mold units are offset in an outward direction relative to side surfaces of the plurality of second mold units to form an alternating, step-like structure, the outward direction being perpendicular to the side surfaces of the plurality of second mold units and being parallel to the top surface of the light supply unit and wherein the bottom cover is coupled with the panel guide mold and supports the light supply unit, and comprises a plurality of first sidewalls spaced apart from each other and a plurality of second sidewalls, wherein each one of the second sidewalls is disposed between two consecutive first sidewalls, and wherein each of the plurality of the first sidewalls is inserted and coupled to a corresponding one of the plurality of first mold units and each of the plurality of second sidewalls receives and is coupled to a corresponding one of the plurality of second mold units, such that where each first mold unit protrudes outward from the side surfaces of the plurality of second mold units, a corresponding first sidewall is recessed inward relative to the side surfaces of the plurality of second side walls and where each second sidewall protrudes outward relative to the side surfaces of the plurality of first sidewalls, a corresponding second mold unit is recessed inward from the side surfaces of the plurality of first mold units.