Abstract: A burglarproofing device for a car-carried acoustic apparatus prevents operation of the car-carried acoustic apparatus if the apparatus is stolen. The device allows only an owner of a car who holds a controller to render the apparatus operative. The controller is in the form of a card having keys for entering a pass number and a memory for storing a pass number thus entered. The pass number is transmitted to the car-carried acoustic apparatus when the controller is inserted into a hole formed in the car-carried acoustic apparatus, and is compared with a verification number stored in discriminating means, and only when coincidence is found, is power made available to the apparatus.