To suppress acceleration performance reduction of a vehicle using compressed air from an air reservoir when the amount of compressed air used increases, by driving a compressor with the power of an engine transmitted to a PTO shaft through a clutch means and storing air compressed by the compressor in an air reservoir.

When driving a diesel engine 1, a turbine wheel 6 rotates by pump activation from the circulation of filled up oil following rotation of an impeller wheel of a torque converter 5 when a lock up clutch 3 is released. Rotation with an increased torque is then transmitted to a turbine shaft 7. A PTO shaft 53 is aligned parallel with the turbine shaft 7 and a sub air compressor 11 is able to be driven as an accessory via a hydraulic clutch 8 and a driven gear 10. Then, the hydraulic clutch 8 is engaged and disengaged with a command signal to suppress the speed from the driver. The hydraulic clutch 8 engages with a command signal to suppress the speed thereby driving the sub air compressor 11. The resultant compressed air is then stored in an air reservoir 42.