A locking device for lock components, for example on vehicles, with two rotary closures which are arranged at a distance from one another and are connected by means of a mechanical transmission element to form a synchronously rotating closure unit and which interact with two catch bolts assigned to the two rotary closures, each located in a housing having an orifice adapted to receive the catch bolts. The two rotary closures of the closure unit, in their release position, are each blocked by means of an associated control member against rotation into locking engagement with the associated catch bolt. The control members are movable into an unblocked position in response to penetration of the catch bolts into the orifice of the housing, and the locking advance of the rotary closures is permitted only after both catch bolts have penetrated fully into the orifice in the housing.