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 (CRC), absorbency under load (AUL), gel bed permeability (GBP), 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.