To improve safety of a worker by forming a clearance signal generation means so as to control the operation of a device only during the operation of a wheel lock means.

A clearance signal generation means 7 is laid within a female member 25, and generates a clearance signal for the air pressure member of a device to feed the air necessary for again inflating a tire, upon the completion of a locking process. Also, prior to the re-inflation of the tire, a worker actuates a fluid drive source mounted on a tire mounting and demounting device 2. The fluid drive source drives a segment including a rod, until the end 26a of the rod is inserted in the female member 25. After the rod is inserted in the member 25, the clearance signal generation means 7 laid within the female member 25 sends a clearance signal necessary for the re-inflation of the tire. In this case, a protection device 1 prohibits the travel of a wheel 6 fixed so as to cross the rod, even upon the burst thereof.