Abstract: A biomass thermochemical gasification apparatus is provided that can manufacture high-quality fuel gas out of solid biomass in an industrial manner. This fuel gas can be used as fuel for a gas engine and a gas turbine for example and also can be used as synthesis gas for methanol synthesis. A high-temperature combustion gas generation apparatus (101) for biomass operates entirely by biomass and the heat source thereof does not depend on fossil fuel. A coarsely-ground powder biomass (205) subjected to gasification and gasification agent (303) are introduced to a primary gasification reaction room (202) and generate gasification reaction by, as reaction heat, radiation heat from a wall face of the primary gasification reaction room (202) heated by combustion gas (109a) generated in the high-temperature combustion gas generation apparatus (101) and are dissolved. Consequently, the biomass (205) is converted to clean and high-quality generated gas.