To provide a lock device improving usability by easily inserting an unlocking key.

In the lock device, which has a cylinder lock 3 in which a rotor 2 is inserted rotatably into a case 1 and the unlocking key 6, which can be inserted into a key inserting hole 4 for the rotor 2 and in which code forming recessed sections 5 are formed to a surface, and in which a relative rotation to the case 1 of the rotor 2 is inhibited or permitted at the places of tumblers 7 in the rotor 2 determined by the notch depths of the code forming recessed sections 5 for the unlocking key 6 inserted up to an insertion-terminal place in the key inserting hole 4, the unlocking key 6 is constituted so as to idly run in the key inserting hole 4, be able to be inserted up to the insertion- terminal place in all idle-running angle postures and be connected in the direction of a rotation to the rotor 2 only at rotary places where the code forming recessed sections 5 positively face the corresponding tumblers 7.