Provided is a water-absorbing agent which maintains a certain degree of liquid permeability and water absorption speed while also reducing re-wet in a disposable diaper, without the use of costly raw materials or costly apparatuses. The water-absorbing agent of the present invention contains a polyacrylic acid salt-based water-absorbing resin as a main component and has physical properties falling within a specific range, the physical properties being saline flow conductivity (SFC), gap fluid retention property under pressure, and a proportion of particles having a particle diameter of not less than 150 μm and less than 710 μm.