The disclosed process for producing a water-absorbing resin comprising: a polymerization step of polymerizing an aqueous unsaturated monomer; a drying step of drying a particulated water-containing gel-liked crosslinked polymer, obtained in a finely crushing step during the polymerization or after the polymerization; a pulverizing step after the drying, a classification step after the drying, and a surface treatment step after the classification. In the process is, the surface-treatment step is interrupted with a heating treatment apparatus kept in a heated state and thereafter the surface treatment step is restarted.