To forcedly perform an exhausting when the fear of rupture (burst) is present to prevent the occurrence of the burst by interposing a manual exhaust valve between a pressure reducing valve and a tire.

A pressure reducing valve 26 is provided with a pressure gauge 29, and a tire internal pressure indicator 11 is arranged in a piping 25 between a manual selector 27 and a coupler 28. The pressure reducing valve 26 automatically exhausts air to a tire set pressure to reduce the pressure when the tire measured pressure is a set pressure or more. In a filling work of air, an air chuck 16 is installed to the valve, the manual selector 27 is set to intake by operation of a cut-off lever, and air filling is then performed. When there is the fear of a burst due to the defect of a tire T, a peculiar cracking sound is generated as an omen during the air filling. In this case, the manual selector 27 is switched to exhaust, whereby the tire internal pressure can be reduced to prevent the burst.