Method for producing aqueous liquid containing vinyl polymer and method for producing water-resistant and oil-resistant agent

The purpose of the present invention is to provide a method for producing an aqueous liquid containing a vinyl polymer, with enhanced production efficiency but without lowering the yield of the vinyl polymer. Production of the aqueous liquid containing the vinyl polymer, by removing a hydrophilic organic solvent from a mixed liquid containing the vinyl polymer, the hydrophilic organic solvent, and water, is characterized by: forming a gas phase and a liquid phase in a sealed container; causing part of the liquid in the liquid phase to form small droplets and bringing the resultant droplets into contact with the gas phase to vaporize the hydrophilic organic solvent; and removing the vaporized hydrophilic organic solvent from the sealed container. Specifically, for example, a mixed liquid 40 is poured, and a liquid phase 50 and a gas phase 51 are formed, in a sealed container 10 having: a liquid inlet 22; a gas outlet 30; a liquid outlet 21; and an external circulation system 20 that connects the liquid inlet 22 and the liquid outlet 21 and has means for adjusting the temperature and pressure of the liquid. The mixed liquid 40 in the liquid phase 50 is circulated from the liquid outlet 21 through the external circulation system 20, and, after the temperature and pressure of the mixed liquid 41 in the external circulation system 20 are adjusted to a condition under which the hydrophilic organic solvent in droplets easily vaporizes in the gas phase 51, the mixed liquid 41 is discharged from the liquid inlet 22 into the gas phase 51 as small droplets while gas in the gas phase 51 is discharged from the gas outlet 30.