To provide an air compression system to eliminate a need for an installation area to install an auxiliary tank and besides intercommunicate an air compressor body and an auxiliary tank.

This air compression system comprises an air compressor body 1 provided with a compressor to compress air and an air tank to store compressed air compressed by the compressor; separate auxiliary tanks 2, 2, and 2 to auxiliarily store compressed air compressed by the air compressor body 1; and a placing plate 12 placed on the air compressor body 1 above the auxiliary tanks 2, 2, and 2. When the air compressor body 1 is placed on a placing bed 12, a female socket 17 placed on the air compressor body 1 side and a male type plug 18 situated on the auxiliary tank 2 side are interconnected and the auxiliary tank 2 and the air tank 1a are intercommunicated.