A backlight unit may be provided which is capable of local dimming. The backlight unit includes: one or a plurality of light emitting devices; and a light guide plate including a top surface and a bottom surface, one or a plurality of grooves which are formed in the bottom surface and in which the light emitting device is disposed, a reflective layer which is disposed within the one or the plurality of grooves and reflects light emitted from the light emitting device, and a plurality of inverse prism patterns disposed in the top surface.