Provided is a water-absorbing resin capable of having a high swollen gel elastic modulus while maintaining a high swelling capacity and a method for producing the same.The problem described above is solved by a water-absorbing resin including a water soluble unsaturated monomer having a dissociable group as a main component of a repeating unit of a main chain, wherein the water-absorbing resin has an internal crosslinked structure, a crosslinked structure index expressed by the following numerical formula 1 is 14 or more, a weight average molecular weight (Mw) of the water-absorbing resin after a hydrolysis treatment is 220,000 or less, and a molecular weight distribution (Mw/Mn) of the water-absorbing resin after a hydrolysis treatment is 3.40 or less:Crosslinked structure index=(Equilibrium swelling capacity with respect to 0.9 wt % physiological saline solution)1/3/(Weight average molecular weight (Mw) after hydrolysis treatment)×1000000 [Numerical formula 1]where the hydrolysis treatment is a treatment to leave 50 mg of the water-absorbing resin as a solids content to stand still in 10 g of a 0.1 mol/l aqueous sodium hydroxide solution for 3 weeks at 80° C., and the weight average molecular weight (Mw) is a value measured after the treatment.In addition, the water-absorbing resin is produced, for example, by a production method including a reaction step for reacting a first star-shaped polymer containing the water soluble unsaturated monomer as a main component of a repeating unit of each branched chain and having a first reactive functional group at a terminal of each branched chain with a second star-shaped polymer containing the water soluble unsaturated monomer as a main component of a repeating unit of each branched chain and having a second reactive functional group capable of forming a chemical bond with the first reactive functional group by reacting with each other at a terminal of each branched chain.
