An angle adjustment apparatus has a first member, a second member, a lock member, and a movement mechanism axially moving the lock member. The first member has first teeth on a surface facing the lock member. The lock member has second teeth and a rotation regulation portion, the second teeth being engaged with the first teeth, the rotation regulation portion being engaged with the second member. The movement mechanism has an input member and a drive member, the input member being regulated from being axially moved relative to the first member or the second member, the drive member being regulated from being axially moved relative to the lock member. A first engagement portions is provided to the external peripheral surface of the input member. A second engagement portion engaged with the first engagement portion is provided to the drive member.