Abstract: A locking device for a lock cylinder (12) has an electronically controlled inhibiting element (2), which in an inhibit position (xS) blocks movement of a rotor (1) relative to a stator (6) and frees the rotor (1) in a free position (xF). A drive (9) exerts a working force (FA) on the inhibiting element (2), by which inhibiting element (2) can be reversibly transferred from the inhibit position (xS) into the free position (xF) and vice versa. A guide (52-57) is connected to the drive (9) and, at least outside the free position (xF), clearly defines the position of the inhibiting element (2). A restoring device (3) exerts a restoring force (FR) directed away from the free position (xF) on the inhibiting element (2), when that element is between the free position (xF) and a rest position (xO). In the rest position (xO) and in positions between the rest position (xO) and the free position (xF), the inhibiting element inhibits movement of the rotor (1).