To provide a method for fractionating a liquid composition, which is excellent in separability of the liquid composition. This method for fractionating a liquid composition comprises discharging, from a discharge port of a filling nozzle, a liquid composition containing a solvent and a polymer having ion exchange groups, and fractionating a predetermined amount of the liquid composition, characterized in that the temperature of the liquid composition is controlled so that the average tan δ1 of the liquid composition when discharged from the discharge port of the filling nozzle becomes to be at most 1.00.