a superabsorbent polymer which has excellent initial absorbency and keeps water from flowing out under load even after the passage of a long period of time is provided , in which centrifuge retention capacity , absorbency under load , gel bed permeability , and absorption rate under load of the superabsorbent polymer are optimized within a predetermined range at the same time . therefore , it is possible to improve physical properties of a final diaper product and to produce a diaper to which an ultra - thin technology is applied .