Abstract: An anti-theft locking device is described for immobilizing a foot pedal assembly normally necessary for operation of an automobile. A first rigid plate, hingably attached to the floor of the automobile adjacent to the foot pedal assembly, can be moved from a stored position on the floor to an immobilizing position blocking access to the foot pedal assembly. A second rigid plate, hingably attached to one end of the first rigid plate, can be folded under the first one in the stored position but, in operation of the device, serves to brace the first plate in the immobilizing position. The second plate is locked in the brace position by means such as a padlock secured to a hoop on the floor of the automobile projecting through an aperture on said plate.The device can be installed as original equipment in an automobile or can be retrofitted thereto at any time during the life of the automobile.