To provide a lock device that enables a door to be easily opened in the case of emergency, and prevents an anti-panic type lock from being unlocked by mischief and so on.

A lock device 11 includes: an escutcheon 23 which has an internal space 31, is fixed to a door surface, and rotatably supports a base shaft 39 of an operation member; a restriction member 25 having a pair of alienation restriction claws 75 which are slidably provided in the internal space 31 in parallel with the wall surface and in a direction in which they approach and leave the base shaft 39, and located across a clamping gap extending in the sliding direction; a lock plate 57 which has its top and reverse surfaces fixed to the base shaft 39 penetrating the internal space 31 in an orthogonal direction, and inhibits rotation of the base shaft 39 as a pair of parallel restricted side parts 71 engage with the clamping gap between the pair of alienation restriction claws 71; and an unlock member 27 which has an unlock part 85 exposed outward from a button opening hole 83 of the escutcheon 23 and moves the restriction member 25 from the restricted side parts 71 in an engagement unlock direction as the unlock part 85 is operated.