A holding apparatus provided with a holding portion for holding a flange
portion of an optical element. The holding portion includes a bearing
surface block having a bearing surface, which contacts the flange
portion, and a bearing surface block support mechanism, which rotatably
supports the bearing surface block about a tangential axis of the optical
element. This structure holds the optical element with the optical
element holding apparatus in a kinematical manner and maintains
satisfactory imaging performance in the optical element.