A lock device comprises a housing (2) which includes an opening (4) and a core (10) which is rotatably disposed in the opening. A latching element (20) co-acts between the housing and the core and can be moved between a release position in which the core is rotatable relative to the housing, and a latching position in which rotation of the core relative to the housing is blocked. An electronically controllable actuator (30) is disposed in the core and is moveable between an opening-registering-position in which the latching element is movable to the release position, and a latching position in which movement of the latching element to said release position is blocked. A returning means (50) co-acts mechanically with a key in a key way in the core and with the actuator and such as to move the actuator away from the position of the opening to a further latching position in response to the key being drawn out of the keyway. Movement of the latching element to said release position is blocked by the actuator in this further latching position. Because the returning means is rotatable there is obtained a small latching mechanism that is returned mechanically to a latching position upon removal of the key.