A saccharide-solution producing apparatus 11A according to the present invention is a saccharide-solution producing apparatus for producing a saccharide solution 22 derived from a carbohydrate-based material 21, and includes a saccharide-solution controlling unit 15A that controls the saccharide solution derived from the carbohydrate-based material 21, a cellulosic biomass saccharifying unit 16 that saccharifies hydrothermally treated biomass obtained by hydrothermally decomposing a cellulosic biomass material 35 that contains a lignin component and a hemicellulose component, and produces a diluted saccharide solution 37, and a diluted-saccharide-solution supply pipe L11 that mixes the diluted saccharide solution 37 produced by the cellulosic biomass saccharifying unit 16 into the saccharide-solution controlling unit 15A. With this configuration, it is possible to improve production efficiency of the saccharide solution 22 and to realize cost reduction.