PURPOSE: To smoothen the automatic lock and lock release by installing a guide part which shifts a crescent in the direction for pulling a crescent receiving part according to the turn in the locking direction of the crescent, on a vertical movable body installed on an installation frame.

CONSTITUTION: When an electric motor 11 is revolved in the normal direction, a worm 13 revolves, and a vertical movable body 10 moves upward by the screwing between the worm 13 and a female screw 14, and a crescent 14 turns in the counterclockwise direction. When the crescent 4 is engaged with a crescent receiving part 19, a crescent shaft 5 is engaged with the guide part 18 of the vertical movable body 10. When the vertical movable body 10 moves upward furthermore, the crescent shaft 5 shifts in the direction X for pulling the crescent receiving part 19. Further, a door on which the crescent 4 is installed and a door on which a crescent receiving part 19 is installed are set close, and locked.