The safety device comprises a chock (2) equipped with an anchoring device (12) which extends onto the ground surface (6) away from the wheel location face (8) by such a distance that a vehicle's wheel (14) lying on the wheel location face by its contact area (16) stands upon the anchoring device or inside it. The anchoring device consists of a flexible mat acting as a support under the wheel contact area and may be a rubber mat or chain mat. The anchoring device also has a rigid plate.
