A device for adjusting and fixing a backrest of a vehicle seat contains a first internal gearwheel (1) which is connected to the underframe of the vehicle seat and has an internal toothing (11), a second internal gearwheel (2) which is connected to the backrest of the vehicle seat and has an internal toothing (21), at least one locking element (6, 7) which is arranged in a radially movable manner on the first internal gearwheel (1) and has an external toothing (61, 71, 72) at least partially covering the internal toothings (11, 21) of the internal gearwheels (1, 2), and a cam disc (3) for controlling the radial movement of the locking element (6, 7) which engages with its external toothing (61, 71, 72) in the internal toothings (11, 21) of the first and second internal gearwheels (1, 2) in a position fixing the backrest, and the external toothing (61, 71, 72) of which locking element is lifted out of the internal toothings (11, 21) of the first and second internal gearwheels (1, 2) in a position for adjusting the backrest.