A crosslinked polymer (A) which comprises, as essential structural units, units derived from (a) one or more vinyl monomers selected from the group consisting of water-soluble vinyl monomers and/or vinyl monomers which become water-soluble upon hydrolysis and units derived from (b) a crosslinking agent and which satisfies the following requirements: (1): (X)25 g/g, (2): (Y)15 g/g, and (3): (Y)-0.54 (X)+41. It has exceedingly high water retentivity and exceedingly high absorbing power under load. When applied to an absorbent structure and an absorbent article, the polymer has excellent absorbing performance. In the relationships, (X) is the amount of physiological saline retained through 1-hour absorption and (Y) is the amount of physiological saline absorbed through 1-hour standing under a load of 60 g/cm².