PURPOSE: A car door locking device is provided to prevent the opening of a door even if a user operates a lock knob or an internal handle in the state that the door is locked. CONSTITUTION: A latch gear(20) restricts a striker installed at the car body. A release unit transfers operation force of an external knob and releases the restriction of the latch gear. An intercepting member is connected with the release unit and blocks the transmission of the operation force of the external knob. A driving unit supplies power to the intercepting member. A driving gear is connected with the driving unit. A deadlock unit restricts the driving gear. A driven gear is installed between the driving unit and the insulating member. Operating force of a lock knob is transferred to the driven gear.
