The amount of water to be injected in an intercooler is controlled to cool the compressed gas to the saturation temperature. It is difficult to adjust the amount of the water to be injected, however, since the temperature of the compressed gas at an intercooler outlet is actually higher than the saturation temperature. An intercooling system is configured so as to cool a gas to the saturation temperature without controlling the amount of water injection and thereby maintain the reliability of the compressor while improving the cooling efficiency.The intercooling system is located between a plurality of compression stages of a gas compressor to cool the gas that has been in the compressor. A desired amount of liquid is sprinkled to cool the compressed gas while restraining inflow of the liquid into the compression stages.