A device for refining molten metal, comprising: an impeller extending in a vertical direction over a ladle in which the molten metal is charged; and a liquid dephosphorization agent supply part disposed over the ladle to supply a molten state liquid dephosphorization agent to a top portion of the molten metal, wherein the liquid dephosphorization agent supply part comprises a melting furnace to melt a solid dephosphorization agent, wherein the impeller comprises: an impeller body; blades provided on an outer circumferential surface of the impeller body; a supply pipe which is disposed inside the impeller body along a lengthwise direction of the impeller body and through which a solid dephosphorization agent in a powder state and a transfer gas are supplied; and blowing nozzles partially passing_through a lower portion of the impeller body in a direction in which a portion of the impeller body crosses an extension direction of the impeller body to blow the solid dephosphorization agent in a powder state and the transfer gas in a direction crossing the supply pipe and communicating with the supply pipe, wherein the blowing nozzles are formed to be downwardly inclined wherein the blades are positioned above the midpoint of a total depth of the molten metal, and the blowing nozzles are positioned under the midpoint of the total depth of the molten metal. an impeller extending in a vertical direction over a ladle in which the molten metal is charged; and a liquid dephosphorization agent supply part disposed over the ladle to supply a molten state liquid dephosphorization agent to a top portion of the molten metal, wherein the liquid dephosphorization agent supply part comprises a melting furnace to melt a solid dephosphorization agent, wherein the impeller comprises: an impeller body; blades provided on an outer circumferential surface of the impeller body; a supply pipe which is disposed inside the impeller body along a lengthwise direction of the impeller body and through which a solid dephosphorization agent in a powder state and a transfer gas are supplied; and blowing nozzles partially passing_through a lower portion of the impeller body in a direction in which a portion of the impeller body crosses an extension direction of the impeller body to blow the solid dephosphorization agent in a powder state and the transfer gas in a direction crossing the supply pipe and communicating with the supply pipe, an impeller body; blades provided on an outer circumferential surface of the impeller body; a supply pipe which is disposed inside the impeller body along a lengthwise direction of the impeller body and through which a solid dephosphorization agent in a powder state and a transfer gas are supplied; and blowing nozzles partially passing_through a lower portion of the impeller body in a direction in which a portion of the impeller body crosses an extension direction of the impeller body to blow the solid dephosphorization agent in a powder state and the transfer gas in a direction crossing the supply pipe and communicating with the supply pipe, wherein the blowing nozzles are formed to be downwardly inclined wherein the blades are positioned above the midpoint of a total depth of the molten metal, and the blowing nozzles are positioned under the midpoint of the total depth of the molten metal.