A backlight unit, comprising: a frame including a bottom area and a sidewall area extended from the bottom area; a substrate positioned in front of the frame; a light source installed on the substrate; a reflecting sheet positioned in front of the substrate; an optical sheet positioned in front of the reflecting sheet; and a holder positioned between the frame and the reflecting sheet, wherein the reflecting sheet comprises: a first sheet region disposed at the bottom area and having a lens hole, a lens being combined to the light source through the lens hole; a second sheet region connected to the first sheet region and disposed at the sidewall area, wherein the second sheet region has a curved surface, wherein an angle formed between the reflecting sheet and the bottom area of the frame increases gradually and has dots in a dot area, wherein the dots influence the reflectivity of the corresponding area, such that light is reflected uniformly from the reflecting sheet; and a chamfer region shaped to be protruding to a front direction and located at the first sheet region, spaced apart from the frame, supported by the holder, wherein the chamfer region includes a chamfer flat area and two chamfer inclination areas, wherein the chamfer inclination area is a part on which dots are located in a chamfer dot area, wherein the dots in the chamfer dot area influence the reflectivity of the corresponding area, such that light is reflected uniformly from the reflecting sheet, wherein the chamfer flat area is a plane connecting both of the chamfer inclination areas and having no dots, wherein the lens is configured to direct the light sideways to the chamfer region and the second sheet region; wherein a diameter of the chamfer dots located within the chamfer dot area is larger than a diameter of dots located within the dot area, and wherein an angle between the chamfer inclination area and the bottom area of the frame is greater than any angle formed between the second sheet region and the bottom area of the frame. a frame including a bottom area and a sidewall area extended from the bottom area; a substrate positioned in front of the frame; a light source installed on the substrate; a reflecting sheet positioned in front of the substrate; an optical sheet positioned in front of the reflecting sheet; and a holder positioned between the frame and the reflecting sheet, wherein the reflecting sheet comprises: a first sheet region disposed at the bottom area and having a lens hole, a lens being combined to the light source through the lens hole; a second sheet region connected to the first sheet region and disposed at the sidewall area, wherein the second sheet region has a curved surface, wherein an angle formed between the reflecting sheet and the bottom area of the frame increases gradually and has dots in a dot area, wherein the dots influence the reflectivity of the corresponding area, such that light is reflected uniformly from the reflecting sheet; and a chamfer region shaped to be protruding to a front direction and located at the first sheet region, spaced apart from the frame, supported by the holder, wherein the chamfer region includes a chamfer flat area and two chamfer inclination areas, wherein the chamfer inclination area is a part on which dots are located in a chamfer dot area, wherein the dots in the chamfer dot area influence the reflectivity of the corresponding area, such that light is reflected uniformly from the reflecting sheet, wherein the chamfer flat area is a plane connecting both of the chamfer inclination areas and having no dots, wherein the lens is configured to direct the light sideways to the chamfer region and the second sheet region; wherein a diameter of the chamfer dots located within the chamfer dot area is larger than a diameter of dots located within the dot area, and wherein an angle between the chamfer inclination area and the bottom area of the frame is greater than any angle formed between the second sheet region and the bottom area of the frame. a first sheet region disposed at the bottom area and having a lens hole, a lens being combined to the light source through the lens hole; a second sheet region connected to the first sheet region and disposed at the sidewall area, wherein the second sheet region has a curved surface, wherein an angle formed between the reflecting sheet and the bottom area of the frame increases gradually and has dots in a dot area, wherein the dots influence the reflectivity of the corresponding area, such that light is reflected uniformly from the reflecting sheet; and a chamfer region shaped to be protruding to a front direction and located at the first sheet region, spaced apart from the frame, supported by the holder, wherein the chamfer region includes a chamfer flat area and two chamfer inclination areas, wherein the chamfer inclination area is a part on which dots are located in a chamfer dot area, wherein the dots in the chamfer dot area influence the reflectivity of the corresponding area, such that light is reflected uniformly from the reflecting sheet, wherein the chamfer flat area is a plane connecting both of the chamfer inclination areas and having no dots, wherein the lens is configured to direct the light sideways to the chamfer region and the second sheet region; wherein a diameter of the chamfer dots located within the chamfer dot area is larger than a diameter of dots located within the dot area, and wherein an angle between the chamfer inclination area and the bottom area of the frame is greater than any angle formed between the second sheet region and the bottom area of the frame.