PURPOSE: To provide an efficient dephosphorization method for high-Mn molten iron.

CONSTITUTION: The dephosphorization of the molten alloy iron is executed by blowing powdery additives 5 for dephosphorization refining formed by mixing ≥1 kinds of powders of oxides of Fe, Cr and Mn with powders consisting of the following (1) and (2) at 10 to 30 pts.wt. in terms of MnO2 with 100 pts.wt. these powders by gas for refining and/or other carrier gases to the surface of the high-Mn molten alloy iron 3 contg. ≥2% Mn. (1) 20 to 90wt.%, in terms of BaO, ≥1 kinds among BaO, BaCO3, Ba(OH)2 and BaSO4. (2) 10 to 80wt.% ≥1 kinds of BaCl2 and BaF2. The above method is also executable under a reduced pressure. As a result, the cost and consumption unit of the flux are decreased and the dephosphorization of the high-Mn molten iron is efficiently executed.