To provide a lock device having an increased degree of freedom of design and capable of being surely locked, and a file having an effectively enhanced security by employing the lock device.

Three dials 2a, 2b, 2c are attached to a face of a lock plate 1 in the face direction of the lock plate 1. Operation protrusions 11a, 11b, 11c as engagement elements and restriction protrusions 21a, 21b, 21c are formed on the dials 2a, 2b, 2c and the lock plate 1 to inhibit the lock plate 1 from moving to an unlocking position (K) when the lock plate 1 is positioned to a lock position (S) by setting the dials 2a, 2b, 2c to a lock position (r) and permit the lock plate 1 to move to the unlocking position (K) by setting the dials 2a, 2b, 2c to a lock-unlocking position (o).