There is provided an evaporating material of thin plate shape which can be manufactured at a reduced cost and at high productivity, the evaporating material being adapted for use in enhancing the coercive force of neodymium-iron-boron sintered magnet by heat treatment while evaporating Dy in vacuum or in reduced-pressure inert gas atmosphere. The evaporating material of this invention has a core member la made of a fire-resistant metal having a multiplicity of through holes, and is made by melting a rare-earth metal or an alloy thereof so as to get adhered to, and solidified on, the core member. In this case, the above-mentioned adhesion is performed by dipping the core member into a molten bath of the rare-earth metal or an alloy thereof, and pulling it out of the molten bath.