To prevent "lockout" and "lock-in" by simplifying a structure.

In a lock device of a latch lock, a lock box 3 comprises a reverse latch 11, a latch spring 12, and a horizontal operating rod 13. A lock piece 14 for the latch is pivotally supported in the lock box. An engaged portion in slidable contact with the rear end part of the lock piece for the latch, a contact part brought into contact with the pressing portion of the horizontal operating rod, and a spring end connection part are formed between the lock piece for the latch and the horizontal operating rod from the center part in the radial outer direction. The lock device further comprises a tumbler 15 rotated by the operating force of an operating member, and a biasing spring 17 which has one end connected to a spring end connection part and the other end connected to a spring end support member 16 in the lock box, and which is displaced from a lock position to an unlock position together with the tumbler.