To provide a cooling system for compressor suction air in an air separation device capable of effectively utilizing cold heat of liquefied gas and cold heat of LNG exhausted into the atmosphere conventionally in gasification facility in the air separation device to improve compression efficiency of a raw material air compressor in the air separation device and reduce consumption power.

This cooling system for compressor suction air is provided with a heat exchanger 41 for cooling raw material air sucked by the compressor on a suction side of the raw material air compressor 13B in the air separation device. The relation of pressure loss ΔP (Pa) of the compressor suction air generated by installing the heat exchanger 41 and difference in temperature ΔT (°C) of compressor suction air between the front and the rear of the heat exchanger 41 is set to satisfy ΔT≥(ΔP/500).