Disclosed are a backlight unit and a display device. The backlight unit includes a bottom cover including first and second longer sides and first and second shorter sides, a light emitting module disposed on at least one of the first and second longer sides and the first and second shorter sides in the bottom cover, a light guide plate having at least a part disposed on the light emitting module in the bottom cover, an optical sheet on the light guide plate, a support member connected to the bottom cover and having at least a part disposed on the optical sheet, and a top cover disposed on the support member and connected to the bottom cover.