Abstract: A cam mechanism of a lens including a cam groove having a conical side face, formed in an inner peripheral surface of a cam ring, and a cam follower which is provided on a lens holder for holding a lens group and which is fitted in the cam groove, so that the cam follower can be moved in an optical axis direction by the movement of the cam ring, spring members provided on the lens holder to elastically support the cam follower in the radial direction of the cam ring, and mounting members provided on the spring members to engage with the cam follower in the radial direction.