The present invention provides: a novel water-absorbing agent, which exhibits an excellent absorption capacity under a load (AAP), gel layer liquid permeation rate under a load (FRUP), saline flow conductivity (SFC), and shape-maintaining property and ball burst strength (BBS) of a swollen water-absorbing agent aggregate, and excellent persistency of these effects for a long time. The water-absorbing agent, which comprises a polymer obtained by a process including the steps of polymerizing and then crosslinking a monomer including acrylic acid and/or a salt thereof, with the water-absorbing agent being characterized by: (1) exhibiting a free swelling capacity of not less than 23 g/g (GV), a gel deformation of not more than 12.5 cm under a short-time load (0.5 hrPT), and a gel deformation deterioration of not more than 3.5 cm under a load with the passage of time (ΔPT); (2) exhibiting a free swelling capacity of not less than 23 g/g (GV), a ball burst strength of not less than 80 gf (BBS), and a deterioration of ball burst strength of not more than 40% (DBBS); or (3) exhibiting a free swelling capacity of not less than 23 g/g (GV), an absorption capacity of not less than 20 g/g under a load of 4.9 kPa (AAP), and a gel deformation of not more than 12.5 cm under a load (16 hrPT).