A gasification apparatus can produce hydrogen-containing gas from biomass with high thermal efficiency at low costs without severe trouble caused by tar generated by pyrolyzing the biomass, while maximizing the gasification rate of the tar. The gasification apparatus includes a biomass pyrolyzing zone for heating biomass in a non-oxidizing atmosphere, and a gas reforming zone for heating the resulting pyrolyzed gas in the presence of steam. A plurality of preheated granules and/or lumps is moved from the gas reforming zone to the biomass pyrolyzing zone, the apparatus reforms the gas generated by pyrolyzing the biomass and pyrolyzes the biomass, using the heat of the granules and/or lumps. The biomass pyrolyzing zone and the gas reforming zone is provided in a single vessel, and at least one partitioning plate is provided between the biomass pyrolyzing zone and the gas reforming zone.