A light blocking apparatus is applied in an illuminating module of a projector. The light blocking apparatus includes a light shield and a support rod securing the light shield. The light shield is positioned in front of a bulb of the illuminating module. The support rod connects the light shield and another apparatus, such as a lamp reflector, so as to position the light shield in front of the bulb. The light shield is employed to block the light reflected from a UV-IR wheel and a color wheel so that the bulb won't be heated again.