Abstract: A device for automatic brake of cars and trucks on striking an obstacle, mainly in reverse driving. The device incorporates two types of impact sensors, one of which is operated by the mudguards, while the second is of a spongy bumper type. The invention's novelty lies in the spongy bumper type sensor, which appears in two alternatives: one alternative is a spongy impact sensor with a rigid casing, and the other is a spongy impact sensor with rubber switches. The device further incorporates means for operating the brakes, including, in the case of vehicles with a hydraulic brake system, an electromagnetic valve installed on the air chamber in the brake booster. A control system enabling reverse driving at a controlled speed is also described.