It is an object to provide a particulate water-absorbing agent having a high fluid retention capacity under pressure and reduced moisture absorption blocking properties, and a method for producing the same.A particulate water-absorbing agent including a water-insoluble metal phosphate including an anion of a phosphoric acid compound and a divalent or trivalent metal cation, the water-insoluble metal phosphate having a crystallite size of less than 0.15 μm, wherein the particulate water-absorbing agent has a fluid retention capacity under pressure of 2.06 kpa of 20 g/g or more.