The optical apparatus includes a first holding member holding an optical element, a second holding member holding the first holding member, and an adjustment mechanism. The adjustment mechanism includes a fulcrum portion provided at one place in a circumferential direction and connecting the first and second holding member so as to allow movements of the first holding member in decentering and tilting correction directions with respect to the second holding member. The adjustment mechanism further includes two decentering adjustment portions arranged in the circumferential direction and each including a first adjusting member, and two tilting adjustment portions arranged in the circumferential direction and each including a second adjusting member. The first and second adjusting members each have an eccentric portion eccentric with respect to its rotation center portion.