Abstract: A locking device is disclosed. It includes a cylindrical common rotor having a guide for guiding key insertion into a key insertion hole. The locking device also includes disc-shaped tumblers. The present invention solves the problem of inconvenience in carrying several individual keys for unlocking the driving part and the non-driving part of the work vehicle. Also, it is possible to effectively maintain the non-driving part of the work vehicle so that the work vehicle can be systematically managed, thereby improving the quality of maintenance service.