A gas cooler effectively prevents or suppresses an outflow of drain water to the outside. The gas cooler includes a casing, a cooling unit, a seal plate, a lead-in port, a lead-out port, and a drain scattering prevention member. The cooling unit is accommodated within the casing and cools gas. The seal plate is provided in the cooling unit and partitions an inside of the casing into an upper space thorough which the gas before passing through the cooling unit flows and a bottom space through which the gas after passing through the cooling unit flows. The gas is led from the lead-in port into the upper space, and the gas is led out of the bottom space via the lead-out port. The drain scattering prevention member is disposed in the bottom space, and collects the drain water, while allowing the gas to pass therethrough.