An apparatus for locking and unlocking a vehicle door with an inner cable (51), with one end connected to a rotor (36) to make a twisting operation in response to the rotation of the rotor (36) of a cylinder lock (21) and the other end connected to a key operation input shaft of a door lock mechanism, is inserted through an outer casing (50) with opposite ends connected to the cylinder lock (21) and the door lock mechanism (22). A locking part capable of elastically engaging with an engaging part provided at a casing included by the door lock mechanism (22) is provided at an end portion of the outer casing (50) at a side of the door lock mechanism. An engagement release inhibiting member (151) which is capable of inhibiting release of engagement of the engaging part (138) with the locking part, is fitted to one of the end portion of the outer casing (50) at the side of the door lock mechanism and the casing to be capable of being displaced between an engagement release allowing position which allows release of engagement and an engagement release inhibiting position which inhibits release of engagement. Therefore, a connecting state of the outer casing to the door lock mechanism can be prevented from being easily released.
