NOVELTY - Apparatus comprises device for carrying out high-temperature processing of a biomass feedstock, cooling unit for cooling biomass solution, enzyme saccharification tank, foreign substance removal unit provided with a solid-solution separation device and microfiltration (MF) membrane, dilution tank, and water separation unit provided with a reverse osmosis (RO) membrane for removing water from the diluted sugar solution to obtain a concentrated sugar solution.    USE - The apparatus is useful for fermenting feedstock biomass e.g. sugarcane and maize for producing sugar solution and products e.g. ethanol and cellulose.    DETAILED DESCRIPTION - Apparatus comprises device for carrying out high-temperature processing of a biomass feedstock, cooling unit (90) for cooling biomass solution that has undergone high-temperature processing, enzyme saccharification tank (103) in which a cooled solution (101B) is enzymatically saccharified, foreign substance removal unit (113) provided with a solid-solution separation device (112) and microfiltration (MF) membrane (113a) for removing water-insoluble substances contained in a sugar solution (104) extracted from the enzyme saccharification tank, dilution tank (132) disposed downstream from the foreign substance removal unit, in which the sugar solution from which water-insoluble substances are removed is diluted by adding water, and water separation unit (116) provided with a reverse osmosis (RO) membrane (116a) for removing water (114) from the diluted sugar solution to obtain a concentrated sugar solution (115).    DESCRIPTION OF DRAWING(S) - The drawing shows schematic view of the apparatus for fermenting feedstock biomass. (Drawing includes non-English language text)    Cooling unit (90)    Cooled solution (101B)    Enzyme saccharification tank (103)    Sugar solution (104)    Solid-solution separation device (112)    Foreign substance removal unit (113)    Microfiltration membrane (113a)    Water (114)    Concentrated sugar solution (115)    Water separation unit (116)    Reverse osmosis membrane (116a)    Dilution tank (132)