To provide a refining method in which a carbonized material originating from a material to be treated is utilized as a resource by stabilizing the production of the carbonized material, reducing the cost, surely and easily carrying out the removal of a combustible gas component contained in the carbonized material and safely and inexpensively storing and preserving the carbonized material.

The carbonized material is obtained by drying a raw material originating from various materials to be treated which is an organic material in a drying furnace 1 and thermally decomposing the raw material in a carbonization furnace 2. The carbonized material is turned to a refined carbonized material by being introduced into a refining furnace 4 and induction-heated by a magnetic field generating means 42 to remove the combustible component in the carbonized material. The steam produced in the drying furnace 1, a thermal decomposition gas produced in the thermally decomposition furnace 2 and the combustible component produced in the refining furnace 4 are combusted in a gas combustion furnace 5 to make harmless. The gas combustion-treated in the gas combustion furnace 5 is released to the outside after being cooled, for example, by a heat exchanger 6.