An optical element 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.