PURPOSE: To make it possible to unlock with one key body by stopping the movement of a chain lock body attracted to a locking magnet, opening and moving the chain lock body in the case of separation, and approaching an unlocking magnet and a lock releasing magnet to the inside of the key body to bear and slide.

CONSTITUTION: An interlocking projection of a closing cover body mounted to a cover section is inserted and fitted to a locking hole 7 of a lock body 6 provided to a wrapping bag and a main body of a box body, and both chain lock bodies 9 are fitted into an interlocking groove of the interlocking projection by attraction of a chain locking magnet 8. After that, in the case of unlocking, a lock body of another magnetic lock is contacted with the lock body 6 a magnetic lock A from the outside, and an unlocking body of the lock body is operated to slide or rotate. Then, a lock releasing magnet in a key body having magnetic force higher than that of a locking magnet 11 in the lock body 6 is moved in the direction of the axis. At the same time, an unlocking magnet in the key body having magnetic force higher than that of the chain locking magnet 8 in the lock body 6 is moved in the direction of the separation. For that purpose, a lock piece in the lock body 6 is attracted to the lock releasing magnet and is moved, the front end thereof is separated from diagonal sections 10 of the chain lock bodies 9 to move both chain lock bodies 9, and it is separated from the chain locking magnet 8. Successively, it gets of the interlocking groove to unlock the lock.