To provide an inexpensive and efficient method for saccharifying wood-based biomass and a method for producing ethanol from the wood-based biomass.

This pre-treatment method of enzyme saccharification of the wood-based biomass in the method for saccharifying the wood-based biomass by performing the hydrolysis treatment and enzyme treatment of the same is characterized by hydrolyzing the wood-based biomass, separating the obtained reaction material to primary saccharide liquid and residues, then performing a pre-treatment process of mixing the residues with an aqueous alkaline solution, and also with an oxide for forming active oxygen.