To provide a highly reliable antitheft device allowing limited specific persons to use a vehicle.

In this antitheft device provided with a fingerprint reading sensor 11 reading fingerprint of a person intending to unlock a vehicle door lock, a memory 13 storing information on fingerprints previously registered, and a control section 15, fingerprint authentication is performed, determining whether or not there is fingerprint matched with information on fingerprints read by the fingerprint reading sensor 11 among information on fingerprints stored in the memory 13 with reference to information on fingerprints read by the fingerprint reading sensor 11 and information on fingerprints stored in the memory 13. As a result of fingerprint authentication, such control is executed that if there is the matched fingerprint, door opening by the person intending to unlock the vehicle door lock is allowed, and if there is no matched fingerprint, door opening by that person is not allowed.