To prevent incomplete locking by completely closing a door by a double sliding door, and performing locking as long as a condition capable of locking is satisfied.

In a state where a door is completely closed in the double sliding door, a crescent lock with a magnet arranges a magnet 18 with a cover on the hook of an outside door fitting and a magnet 15 with a cover used for a stopper in the inside of the body fitting 5 of an inside door respectively so that the moving direction of the door and the direction of a magnetic line of force are at right angles, in this condition, the two magnets are opposite to be the maximum attracting force, the stopper 13 in a body is released by the attracting force (magnetic force), and the rotary lever 1 of the lock can be rotated by a hand. The attaching position of the lock is made the hook 19 of the outside door seeing from the inside of a room and the stopper 13 of the body inside of the inside door. Thus, in the case where the rotary lever of the lock is at a locking position, locking can be completely performed, and in the case where it is not at the locking position, it is clear that locking is not performed.