An intake air control system comprising: a charge air cooler (100, 100X) comprising: a first heat exchanger for cooling a first refrigerant; a second heat exchanger for cooling a second refrigerant cooler than the first refrigerant; a high temperature side cooling flow path through which the first refrigerant cooled by the first heat exchanger flows; a low temperature side cooling flow path through which the second refrigerant cooled by the second heat exchanger flows; a high temperature side heat exchanger that is provided on the high temperature side cooling flow path and cools, by the first refrigerant, supercharged intake air; and a low temperature side heat exchanger that is provided on the low temperature side cooling flow path and cools, by the second refrigerant, intake air cooled by the high temperature side heat exchanger characterized by a bypass pathway provided on an intake air flow passage downstream of the high temperature side heat exchanger in parallel with the low temperature side heat exchanger; and a thermostatic regulating valve for controlling the temperature of intake air to be supplied to an internal combustion engine by regulating a flow rate of intake air that has exchanged heat at the low temperature side heat exchanger and a flow rate of intake air that has flown through the bypass pathway, a switching valve disposed upstream of the high temperature side heat exchanger, wherein any one of compressed intake air that was compressed by a supercharger and natural intake air that did not flow through the supercharger is selectively supplied to the high temperature side heat exchanger by the switching valve. a charge air cooler (100, 100X) comprising: a first heat exchanger for cooling a first refrigerant; a second heat exchanger for cooling a second refrigerant cooler than the first refrigerant; a high temperature side cooling flow path through which the first refrigerant cooled by the first heat exchanger flows; a low temperature side cooling flow path through which the second refrigerant cooled by the second heat exchanger flows; a high temperature side heat exchanger that is provided on the high temperature side cooling flow path and cools, by the first refrigerant, supercharged intake air; and a low temperature side heat exchanger that is provided on the low temperature side cooling flow path and cools, by the second refrigerant, intake air cooled by the high temperature side heat exchanger characterized by a bypass pathway provided on an intake air flow passage downstream of the high temperature side heat exchanger in parallel with the low temperature side heat exchanger; and a thermostatic regulating valve for controlling the temperature of intake air to be supplied to an internal combustion engine by regulating a flow rate of intake air that has exchanged heat at the low temperature side heat exchanger and a flow rate of intake air that has flown through the bypass pathway, a switching valve disposed upstream of the high temperature side heat exchanger, wherein any one of compressed intake air that was compressed by a supercharger and natural intake air that did not flow through the supercharger is selectively supplied to the high temperature side heat exchanger by the switching valve. a first heat exchanger for cooling a first refrigerant; a second heat exchanger for cooling a second refrigerant cooler than the first refrigerant; a high temperature side cooling flow path through which the first refrigerant cooled by the first heat exchanger flows; a low temperature side cooling flow path through which the second refrigerant cooled by the second heat exchanger flows; a high temperature side heat exchanger that is provided on the high temperature side cooling flow path and cools, by the first refrigerant, supercharged intake air; and a low temperature side heat exchanger that is provided on the low temperature side cooling flow path and cools, by the second refrigerant, intake air cooled by the high temperature side heat exchanger characterized by a bypass pathway provided on an intake air flow passage downstream of the high temperature side heat exchanger in parallel with the low temperature side heat exchanger; and a thermostatic regulating valve for controlling the temperature of intake air to be supplied to an internal combustion engine by regulating a flow rate of intake air that has exchanged heat at the low temperature side heat exchanger and a flow rate of intake air that has flown through the bypass pathway, a switching valve disposed upstream of the high temperature side heat exchanger, wherein any one of compressed intake air that was compressed by a supercharger and natural intake air that did not flow through the supercharger is selectively supplied to the high temperature side heat exchanger by the switching valve.