A light blocking member according to the present disclosure is for a projection video display device provided with an optical system that projects video light and a projection lens on which the video light is incident, the light blocking member being disposed between the optical system and the projection lens, the light blocking member including: a first light blocking portion that absorbs and converts into heat a part of unnecessary light unnecessary for the projection lens in the video light; and a reflector that reflects, as reflected light, light that is a part of the unnecessary light and that is not absorbed by the first light blocking portion.