The invention relates to an automobile door locking device that comprises: an engaging mechanism that engages with a striker; external operating switches SW1, SW3, SW10; an inside handle IH; a lockingand unlocking mechanism that can selectively switch between an unlocked state in which the engaging mechanism can be disengaged and a locked state in which the engaging mechanism cannot be disengagedon the basis of door opening operations by the inside handle IH; a controlling device ECU that authenticates a transmitter SW6 on the basis of a signal issued by the transmitter and, when the transmitter is outside the vehicle, validates operation of an external operating switch when the transmitter is authenticated and invalidates operation of the external operating switch when the transmitter is not authenticated; and an electric release mechanism that can disengage the engaging mechanism even when the locking and unlocking mechanism is in either the unlocked state or the locked state by way of a release drive of an electric motor 22 for releasing by way of the controlling device on the basis of operation of the external operating switch when the controlling device has authenticated thetransmitter outside of the vehicle.