A backlight unit including a bottom cover having a bottom surface and a sidewall extending from the bottom surface, light sources, and a reflection sheet. Outermost ones of the light sources are configured to include a first light source and a second light source. The first light source and the second light source have different distances from the sidewall. The reflection sheet includes a first reflection sheet disposed between the sidewall and the first light source and a second reflection sheet disposed between the sidewall and the second light source. The first reflection sheet and the second reflection sheet have different inclined angles from each other.