Method for manufacturing water absorbent resin

A method for manufacturing a water-absorbent resin, comprising:

• a cleaning step of cleaning an inside of a heat exchanger that is connected to a vessel holding an aqueous gel-like polymer as a precursor of the water-absorbent resin and is configured to cool a gas containing the polymer produced in the vessel, wherein the heat exchanger comprises:
• a plurality of pipes that have elongated paths through which the gas passes, and in which the gas is cooled due to heat dissipation during passage through the paths;
• a chamber that is arranged above the plurality of pipes and is in communication with openings at upper ends of the plurality of pipes;
• and
• a cleaner that sprays a cleaning liquid in the chamber,
• wherein the cleaning step comprises at least cleaning an inside upper surface of the chamber located above the openings to the plurality of pipes and an inner wall surface of the plurality of pipes by spraying the cleaning liquid from the cleaner in the chamber.