Provided are a backlight unit and a holographic display apparatus including the same. The backlight unit includes a light guide plate; an input coupler configured to guide light into the light guide plate; a light deflector configured to deflect light emitted from the input coupler and guide the deflected light to propagate within the light guide plate. The light deflector is disposed on a region of the light guide plate which does not overlap with an optical path of light incident on the input coupler. The backlight unit also includes an output coupler configured to emit the light, having been propagated within the light guide plate, to an outside of the light guide plate.