Disclosed is herein a teeth whitening apparatus. The teeth whitening apparatus according to the present invention includes a mouth gap inserted into a users oral cavity so as to be in close contact with his or her teeth, and a main body connected to the mouth gap by means of a cable and configured to supply power to the mouth gap, the main body having a switch configured to control an ON/OFF operation, wherein the mouth gap includes: a body formed in a flat rectangular parallelepiped shape which is curved in its entirety, the body having an accommodating space formed therein and an opening formed at one side thereof a light-emitting unit mounted in the accommodating space of the body and including a PCB embedded with a plurality of light-emitting devices and an oral cavity wearing unit including a coupling member detachably coupled to the outer periphery of the opening of the body and having a vent aperture formed at the center thereof and an insertion member formed at one side of the coupling member so as to be inserted into the users mouth and brought into close contact with his or her teeth, and wherein the insertion member comprises a pair of opposed holding protrusions protrudingly formed inwardly from the inner surface thereof so as to be held between his or her upper and lower teeth, the insertion member having one or more elongated vent holes formed thereon in such a manner as to be perforated in a predetermined length to have air permeability.
