A display device comprising: a display panel; and a backlight unit providing light from a lower side of the display panel, wherein the backlight unit comprises: a bottom cover; a light source module mounted on the bottom cover and including: a plurality of light sources arranged at uniform intervals; and a circuit board on which the plurality of light sources are mounted; a reflective layer placed above the light source module to reflect the light emitted from the light sources towards the display panel; a screening layer disposed over the reflective layer at a distance therefrom and having a plurality of patterned holes to allow only a portion of the light reflected from the reflective layer to be transmitted; and a spacer disposed between the reflective layer and the screening layer to form a light guide layer defined by a vacant space between the reflective layer and the screening layer and to maintain the uniform height of the light guide layer, characterized in that the spacer comprises a plurality of protrusions and a plurality of recessed portions (652, 653) which are alternately formed on top and bottom surfaces of the spacer, wherein the plurality of protrusions are adhered to the reflective layer and the screening layer by an adhesive. a display panel; and a backlight unit providing light from a lower side of the display panel, wherein the backlight unit comprises: a bottom cover; a light source module mounted on the bottom cover and including: a plurality of light sources arranged at uniform intervals; and a circuit board on which the plurality of light sources are mounted; a reflective layer placed above the light source module to reflect the light emitted from the light sources towards the display panel; a screening layer disposed over the reflective layer at a distance therefrom and having a plurality of patterned holes to allow only a portion of the light reflected from the reflective layer to be transmitted; and a spacer disposed between the reflective layer and the screening layer to form a light guide layer defined by a vacant space between the reflective layer and the screening layer and to maintain the uniform height of the light guide layer, characterized in that the spacer comprises a plurality of protrusions and a plurality of recessed portions (652, 653) which are alternately formed on top and bottom surfaces of the spacer, wherein the plurality of protrusions are adhered to the reflective layer and the screening layer by an adhesive. a bottom cover; a light source module mounted on the bottom cover and including: a plurality of light sources arranged at uniform intervals; and a circuit board on which the plurality of light sources are mounted; a reflective layer placed above the light source module to reflect the light emitted from the light sources towards the display panel; a screening layer disposed over the reflective layer at a distance therefrom and having a plurality of patterned holes to allow only a portion of the light reflected from the reflective layer to be transmitted; and a spacer disposed between the reflective layer and the screening layer to form a light guide layer defined by a vacant space between the reflective layer and the screening layer and to maintain the uniform height of the light guide layer, characterized in that the spacer comprises a plurality of protrusions and a plurality of recessed portions (652, 653) which are alternately formed on top and bottom surfaces of the spacer, wherein the plurality of protrusions are adhered to the reflective layer and the screening layer by an adhesive. a plurality of light sources arranged at uniform intervals; and a circuit board on which the plurality of light sources are mounted; a reflective layer placed above the light source module to reflect the light emitted from the light sources towards the display panel; a screening layer disposed over the reflective layer at a distance therefrom and having a plurality of patterned holes to allow only a portion of the light reflected from the reflective layer to be transmitted; and a spacer disposed between the reflective layer and the screening layer to form a light guide layer defined by a vacant space between the reflective layer and the screening layer and to maintain the uniform height of the light guide layer, characterized in that the spacer comprises a plurality of protrusions and a plurality of recessed portions (652, 653) which are alternately formed on top and bottom surfaces of the spacer, wherein the plurality of protrusions are adhered to the reflective layer and the screening layer by an adhesive.