[PROBLEMS] To provide a water absorbent resin capable of exhibiting a high swelling gel elastic modulus while maintaining a high swelling ratio, and a method for producing the same.[MEANS FOR SOLVING PROBLEMS] A water absorbent resin having a water-soluble unsaturated monomer having a dissociation group as a main component of a main chain repeating unit and having an internal cross-linking structure and having a cross-linking structure index of 14 or more, Wherein the average molecular weight (Mw) is 220,000 or less and the molecular weight distribution (Mw / Mn) after the hydrolysis treatment is 3.40 or less.[Equation 1]Cross-linking structure index = (equilibrium swelling magnification for 0.9 wt% saline solution)1/3/ Weight-average molecular weight (Mw) after hydrolysis treatment) 1000000Here, the hydrolysis treatment is a treatment in which 50 mg of a water absorbent resin as solid content is allowed to stand in 10 g of 0.1 mol / l aqueous sodium hydroxide solution at 80 for 3 weeks, and the weight average molecular weight (Mw) Respectively. The water absorbent resin can be obtained, for example, by mixing the first star polymer having the water-soluble unsaturated monomer as a main component of the repeating unit of each branched chain and having the first reactive functional group at the end of each branched chain, And a second star polymer having a second reactive functional group capable of reacting with the first reactive functional group at the end of each branched chain to form a chemical bond, as a main component of the repeating unit of the branched chain, [과제] 높은 팽윤 배율을 유지하면서, 게다가 높은 팽윤 겔 탄성률을 나타내는 것이 가능한 흡수성 수지 및 그의 제조 방법을 제공한다.[해결 수단] 해리기를 갖는 수용성 불포화 단량체를 주쇄의 반복 단위의 주성분으로 하고, 내부 가교 구조를 갖는 흡수성 수지이며, 하기 수학식 1로 표시되는 가교 구조 지수가 14 이상이고, 또한 가수 분해 처리 후의 중량 평균 분자량(Mw)이 220000 이하이고, 또한 가수 분해 처리 후의 분자량 분포(Mw/Mn)가 3.40 이하인 것을 특징으로 하는 흡수성 수지에 의해 상기 과제는 해결된다: [수학식 1]가교 구조 지수=(0.9중량% 식염수에 대한 평형 팽윤 배율)1/3/가수 분해 처리 후의 중량 평균 분자량(Mw))×1000000여기서, 상기 가수 분해 처리란
