A backlight unit is disclosed. The backlight unit includes a light emitting device module, a reflective plate including at least two slopes configured to reflect light emitted from the light emitting device module to an optical member, and the optical member to transmit the light directed from the light emitting device module and the reflective plate. The slope located farther from the light emitting device module has a greater gradient with respect to a horizontal plane than the slope located closer to the light emitting device module.