A safety locking device for a shaft door of an elevator and a method for opening the shaft door using the safety locking device involve a shaft door lock having: a first stopper stopping the shaft door at a closed first position wherein the lock locks the shaft door; an emergency release mechanism manually releasing the lock allowing movement in an opening direction; a second stopper stopping the shaft door at a semi-open second position between closed and open wherein the lock locks the shaft door; and at least one counter-stopper engaging with the first stopper to stop the shaft door at the first position and engaging with the second stopper to stop the shaft door at the second position.