This specification discloses a polarizing. element for dividing light into first and second polarized lights differing in polarized state from each other by a polarizing dividing surface, directing the first polarized light in a first direction, reflecting the second polarized light by a reflecting surface and directing it in the first direction, and varying the polarized state of at least one of the first and second polarized lights to thereby make the polarized states of the first and second polarized lights coincident with each other, characterized in that the polarizing dividing surface is disposed on one surface of a plane parallel plate and the reflecting surface is disposed on the other surface of the plane parallel plate, and the light enters obliquely from the one surface or the other surface. The specification also discloses a polarizing conversion unit provided with such polarizing element, and a projector provided with such polarizing conversion unit.