A method of separating a liquid atomizes a mixed liquid containing a plurality of components into an atomized fine particle by an ultrasonic vibration to obtain a mixed fluid of the atomized fine particle and air, separates the air from the mixed fluid and collects an atomized component, and separates the atomized component into liquids having different component contents. The method of separating a liquid atomizes the liquid while supplying a carrier gas heated with the thermal energy of the outside air to the surface of the liquid to be atomized or supplies the outside air to the surface of the liquid to be atomized, thereby atomizing the liquid while supplying the thermal energy of the outside air to the surface of the liquid.