An apparatus which comprises: a carbonizer (1) which pyrolyzes a biomass to yield a pyrolysis gas and a carbonization product; a furnace (2) in which the carbonization product supplied from the carbonizer (1) is burned; a closed vessel (3) which is disposed in the furnace (2) and holds therein a carbonate (4) which has been melted by the heat generated by the carbonization product burned in the furnace (2); an introduction pipe (5) disposed so that the pyrolysis gas is introduced into the molten carbonate (4) in the closedvessel (3); and a fuel gas supply pipe (6) disposed so that a fuel gas, which is the pyrolysis gas sent through the introduction pipe (5), passed through the molten carbonate (4), and purified by reaction with the molten carbonate (4), is sent from the closed vessel (3) to the outside of the furnace (2).