An apparatus for axial locking of a bucket includes a depressed portion formed on an end portion of a male dovetail extending from a bucket and on an outer side of a seating groove of a female dovetail disposed on an outer circumferential surface of a rotor disk, and a locking member disposed in the depressed portion and configured to contact the male dovetail and the seating groove of the female dovetail to prevent the bucket mounted on the rotor disk from being separated in the axial direction.