To provide a compressed air supply system capable of reducing the electric power consumption.

This compressed air supply system 20 has a dry type (nonlubricated type) compressor (screw compressor) 24, an aftercooler 40 for cooling the air compressed by the compressor 24, and a dehumidifier for dehumidifying the air cooled by the aftercooler 40. The compressed air supply system 20 has a low temperature economizer 42 for heat exchanging between the air cooled by the aftercooler 40 and the air dehumidified by the dehumidifier 44, and a high temperature economizer 34 for heat exchanging between the air discharged from the low temperature economizer 43 through the dehumidifier 44 and the air discharged from the compressor 24. The ratio of the air flow passing through the high temperature economizer 34 to the air flow sent from the compressor 24 to the aftercooler 40 is adjusted by a flow control valve 32.