Abstract: The invention relates to a reactor (1) for gasifying biomass, in particular wood, comprising a feeder chute (7) and an ash bed arranged beneath the feeder chute (7). According to the invention, a device is provided by means of which biomass adhering to the feeder chute (7) can be detached, and/or a heat exchanger is provided by means of which a product gas generated from the biomass gives oil heat to the biomass subsequently conveyed in the feeder chute (7) and to oxidation air. The invention further relates to a fine filter (29) for cleaning a product gas generated from biomass. According to the invention, the filter medium contains biomass. Furthermore, the invention relates to a method for gasifying biomass in a reactor (1), in particular a reactor (1) according to the invention, to form a product gas. According to the invention, biomass adhering to the feeder chute (7) is detached and/or heat is given off to biomass and to oxidation air by the product gas.