PURPOSE: To prevent projection to the indoor side at the time of operation by operating a rocking lever centering around a pivot parallel with the direction of movement of a door and engaging and disengaging a hook section to a receiver.

CONSTITUTION: An operating section 11 is moved freely along the axial center of a pivot 12 on the side of a lock base section 10 when the second arm section 15b of a lever section 15 is brought to a horizontal state, thus forwarding and retreating a hook section 18 on the reverse side in the lock base section 10. When the lever 15 is pushed in under the state, the lever 15 can be rotated in the vertical direction, and the hook 18 under a projected state is also tuned together. Such a locking tool 6 is fitted onto the end face 3a of an indoor door 3 by mounting screws 30. Even when the operating section 11 is drawn out to the side from the lock base section 10 at that time, the place of the operating section 11 is adjusted so that the operating section 11 is not projected from the indoor side face 3b of the indoor side door 3. The place of the hook section 18 is adjusted so that the hook section 18 is projected by a fixed length from the outdoor side face 3c of the indoor side door 3 when the operating section 11 is pushed in.