[PROBLEM] It is an object of the present invention to efficiently obtain efficiently a water-absorbent resin having excellent property. [SOLUTION] A production method for a water-absorbent resin, comprising: a polymerization step for obtaining hydrogel by subjecting a monomer aqueous solution to a polymerization reaction； and a drying step for drying the hydrogel； wherein drying in the drying step is performed using a continuous through-flow belt-type drying machine； solid content of the hydrogel supplied to the drying step is 35% by weight or more, and thickness variation rate (1) represented by the following EXPRESSION 1 of the hydrogel loaded onto through-flow belt in the continuous through-flow belt, is 1.05 to 5: EXPRESSION 1 Thickness variation rate 1 = Maximum thickness of hydrogel in a width direction of the through - flow belt / Average thickness of hydrogel in a width direction of the through - flow belt .
