Provided are a method and a refining device for producing molten steel of outstanding cleanliness, and more particularly provides a method and device for refining inclusions by forming droplets from molten steel and dropping same into slag during pre-processing in a continuous casting process in a steel-making process. Also, provided is a method for producing high cleanliness molten steel comprising a molten-steel supply device for supplying molten steel and a molten-steel refining device for containing and refining molten steel poured into the molten-steel supply device, wherein the method comprises: a molten-steel pouring step in which molten steel is poured from the molten-steel supply device into the molten-steel refining device; a droplet-forming step in which the molten steel which has been poured in is formed into droplets in the molten-steel refining device; a slag-pass-through step in which the molten steel which has been formed into droplets is dropped so as to pass through slag; and an inclusion-removing step in which residual inclusions in the molten steel, which has been formed into droplets, are removed while passing through the slag.