Disclosed is switch lock device of a railway switching actuator connected to a switching slide and a tie bar/locking slide of the actuator, the switching slide and a tie bar/locking slide being slidable one over the other to lock a blade of a railway switch in a closed position, the switch lock including an oscillating catch unit oscillating between two positions, engaging either a stationary step of a casing of the actuator or a head surface of the switching slide. The oscillating catch unit links to the end of the tie bar by a spring actuated mechanism blocking oscillation of the oscillating catch unit in an unlocked position corresponding to the engagement of the switching slide. During switching, the tie bar compresses the spring actuated mechanism, and the oscillating catch unit is free to oscillate towards a locking position, engaging the step of the casing of the actuator.