An optical apparatus having a first member and a second member rotating about an optical axis with respect to the first member. One of the members has a cam portion; the other has a cam follower portion engaged with the cam portion which drives the first and second members relatively in an optical axis direction. The first member has first and second portions protruding toward the second member side separated from each other in the optical axis direction; the second member has third and fourth portions protruding toward the first member side separated from each other in the optical axis direction and abuts on the first and second portions, respectively; and the fourth portions are provided in a circumferential direction of the second member and include protruding portions for transmitting power.