Abstract: The present invention provides an indexing driving device for a turntable, which is provided with a plurality of roller followers arranged at equal angular intervals; and a barrel component, which is provided on one side of the turntable, the cam component is provided with a first side rib wall with a continuous cam curved surface in a first direction and a second side rib wall with a continuous cam curved surface in a second direction, and the first side rib wall and the second side rib wall are facing opposite sides to form a cam groove with variable groove width, for introducing the roller followers and rotating the turntable; wherein the cam groove with variable groove width makes the first side rib wall and the second side rib wall respectively pre-compress to at least one pair of the roller followers of the turntable symmetrically in different directions, so as to effectively eliminate the backlash problem between the cam component and the roller followers and improve the positioning accuracy of the tur