A movement mechanism for a movable body including a motor including a rotation shaft, a supporting member that supports the motor, an attachment member fixed to a base body portion and to which the supporting member is attached, a driving pulley coupled to the rotation shaft, a driven pulley attached to the base body portion, an endless belt stretched between the driving pulley and the driven pulley, and the movable body attached to the endless belt, in which the supporting member is configured to be pivotally movable about a position serving as a pivotal axis such that a distance between the driving pulley and the driven pulley shortens, the position being at a side of the driven pulley from the driving pulley in a stretching direction in which the endless belt is stretched between the driving pulley and the driven pulley.