To improve a rate of operation of a vehicle without deteriorating running stability and steering stability, reduce air consumption at normal running to reduce a load of a compressor, and enhance fuel economy, by promptly adjusting a vehicle height in accordance with a change of the height based on a loading/unloading of cargoes at loading in a vehicle stopping state.

This device comprises an air tank 24 which supplies air to air springs 10, 12, and a leveling valve 18 which detects a change in a vehicle height, supplies/discharges air to/from the air springs 10, 12 and adjust the vehicle height. An air flow adjusting means 44 which enlarges an area of an air passage at the time of loading of cargoes and which reduce the area of the air passage at the time of normal running is provided in the air passage through which the leveling valve 18 and the air springs 10, 12 are connected. Preferably, in an air passage through which the air tank 24 and the leveling valve 18 are connected is provided with a second air flow adjusting means 56.