Provided is a water-absorbing agent which has an excellent ability to absorb water and hold the water and also has an excellent liquid-sucking ability. The water-absorbing agent contains a polyacrylic acid (salt)-type water-absorbable resin as the main component, and meets all of the following physical requirements (a) to (e): (a) the weight average particle diameter (D50) is 300 µm or more and less than 400 µm； (b) the content of particles each having a particle diameter of 600 µm or more and less than 850 µm is less than 10% by weight； (c) the average gap radius is 100 µm or more and less than 180 µm； (d) the CRC is 28 g/g or more and less than 34 g/g； and (e) the AAP is 24 g/g or more.
