A method for filling a particulate water absorbing agent includes a filling step of filling a particulate water absorbing agent into a filling container and a vibrating step of vibrating the filling container at the outside of the filling container, the vibrating step being conducted at least one time between the start and the end of the filling step, in which a vibration condition in the vibrating step satisfies the following conditions (a) and (b):(a) vibration by a vibrating body in contact with the filling container has a vertical directional component and a vibrational angle is within 90°±30°; and (b) total amplitude at no load and a vibration frequency at no load of the vibrating body are set so as to satisfy Equation 1-1 and Equation 2 or Equation 1-2 and Equation 2.