To provide a lock device having a high reliability on an operation and having an excellent usability.

The lock device has a lock operating section 3 being driven at places corresponding to a locking and an unlocking by a cylinder lock 1 on the outdoor side and operating the locking body 2 between the places corresponding to the locking and the unlocking and an indoor-side operating section 4 moving the lock operating section 3 between the places corresponding to the locking and the unlocking from the indoor side. A play capable of moving the indoor-side operating section 4 by a stroke between the places corresponding to the locking and the unlocking of the lock operating section 3 in the opposite operating direction is formed between the indoor-side operating section 4 and the lock operating section 3. The indoor-side operating section 4 is constituted in a restrainable manner at the terminal of a play-side stroke.