Method for enzymatically producing bioethanol using cellulosic biomass as starting material

The present invention addresses the problem of providing a method for producing bioethanol using a lignocellulosic biomass as a starting material, wherein the ethanol concentration of a fermented liquid obtained in a fermentation step can be increased and the distillation load can be reduced without requiring any special equipment in solubilizing cellulose contained in the biomass by enzymatic hydrolysis. When hemicellulose is removed from a cellulosic biomass and the resultant solid residue is mixed with an aqueous solution containing a cellulose hydrolytic enzyme in a reaction container, the concentration of ethanol is controlled to 3-6 mass% inclusive. Thus, the growth of miscellaneous microorganisms can be prevented during the hydrolysis of the cellulose and the ethanol concentration can be increased when a saccharified solution is subjected to ethanol fermentation. As a result, the distillation load is reduced. The ethanol added at the hydrolysis can be recovered in the step for distilling the alcohol fermented liquid and then reused.