A backlight unit includes a lower container including a bottom surface which is flat, an optical member accommodated in the lower container, having a concave curve along one direction of the bottom surface and protruding toward a center portion of the bottom surface, a plurality of supporters which contacts the bottom surface and projects toward the optical member to support the optical member, and a plurality of light sources disposed on the bottom surface and arranged between the optical member and the bottom surface, where a density of the plurality of light sources increases along the one direction towards the center portion of the bottom surface.