NOVELTY - Biomass is injected into a gasifier (1) and thermally decomposed in a reducing environment to obtain pyrolysis gas. The pyrolysis gas is supplied to a reformer (2) and modified into reformed gas. The reformed gas is guided to a dust collector (3) and ash content is removed from reformed gas. The ash content is injected into an incinerator (6) and carbon content is burned. Air is supplied to the heat exchanger (7) and air which exchanges heat with heat produced by the incinerator is supplied to the gasifier as combustion air.    USE - Gasification of biomass, such as wooden waste material, to produce fuel gas used for electric-power generation.    ADVANTAGE - The method enables effective usage of incineration heat and carries out reclamation of carbon content in incinerated ash. Supplementary fuel used for the incinerator is reduced. Since heat-exchanged air is used for combustion in gasifier, fuel supplied to the gasifier is reduced.    DETAILED DESCRIPTION - Biomass is injected into a gasifier (1) and thermally decomposed in a reducing environment of excess air ratio of 1 or less, to obtain pyrolysis gas. The pyrolysis gas is supplied to a reformer (2) provided at the later stage of the gasifier and modified into reformed gas. The reformed gas is guided to a dust collector (3) provided at the later stage of the reformer, and ash content is removed from the reformed gas. The ash content is injected into an incinerator (6) provided adjacent to the gasifier, and carbon content contained in ash content is burned. Air is supplied to the heat exchanger (7) provided at the later stage of the incinerator, and air which exchanges heat with heat produced by the incinerator is supplied to the gasifier as combustion air. An INDEPENDENT CLAIM is included for biomass gasifier.    DESCRIPTION OF DRAWING(S) - The drawing shows an explanatory view of the biomass gasification method. (Drawing includes non-English language text)    Gasifier (1)    Reformer (2)    Dust collector (3)    Incinerator (6)    Heat exchanger (7)