Abstract: The subject of the invention is an actuating device for a disc brake for motor vehicles or trailers having opposed brake jaws 5, 8 on both sides of a brake disc, which cooperates with a traction and a pressure rod, while between the traction rod 6 and the pressure rod 7 are arranged pairs of wedges consisting of outer wedges 10 and inner wedges 11. To provide this actuating device with a simply constructed and automatically acting resetting device for compensating for wear of the brake linings, there is provided an automatic resetting device between the inner wedges 11, consisting of a threaded bolt 17 with wedge pieces 18 lying between the inner wedges 11 and a reset lever, which is arranged with a movable collar 20 on the threaded bolt 17, cooperating with a stationary slide 21.