The present invention discloses an apparatus for thermally refining phosphorus. The apparatus comprises: a melting furnace for melting rock phosphate into melts, including a feed port and a melt outlet; and a reduction-oxidation furnace including a furnace body which gas a melt inlet, a slag outlet, and a fume outlet, and a blow gun, wherein the melt inlet and the melt outlet are in communication with each other and wherein the blow gun has an end inserted into the furnace body. The content of impurities in fumes containing phosphorus pentaoxide is low, and the phosphorus pentaoxide can be easily extracted with a high purity of the phosphorus pentaoxide and at low cost by means of the apparatus for thermally refining phosphorus according to the present invention.