<p>A vehicular anti-theft system which combines a mechanical key and an electronic key involving a code light signal. A light emitting element is provided in a casing attached to a base end of the shank of the mechanical key while a light receiving element is provided adjacent to an open end of the key hole so that the conventional action of fitting the key shank into the key hole causes the transmission of a code light signal between these elements. Advantageously, the light emitting element can be additionally equipped with the function of locking and unlocking a vehicle door so that the user can obtain the benefits of both a remote control entry system and a highly effective anti-theft engine start system.</p>
