To prevent a car theft such that a keyhole is broken to operate an engine by mounting a native barcode on the side surface of an automotive key, and mounting a sensor on a keyhole so that the engine is operable only with a normal key.

When a key 1 is inserted to a keyhole 3 on the side of a handle 6, and a barcode provided on the shank side surface of the key 1 is read by a sensor 4 provided on the keyhole 3 and collated with a numerical value stored in an interlocking computer 5. When it is conformed, a current is carried from a battery 7 to a sel-motor to start an engine. Namely, when the key 1 is inserted to the keyhole 3 and turned, the handle lock is released, and when the key 1 is further turned, the self-starting motor is rotated to start the engine. When the numerical value of the barcode is not conformed, the engine is not started. Even if the keyhole 3 is broken to directly connect a wiring, the current is never carried from the battery 7 to the self-starting motor. Further, any spare key cannot be formed. According to this, the theft preventing effect can be enhanced.