A saccharification reaction mixture, a saccharification enzyme composition, and a saccharide production method are aimed to enhance saccharization rate by use of an enzyme in a simple step as well as a method for producing ethanol from a saccharide. The saccharification reaction mixture can saccharify at least one of cellulose and hemicellulose and contains at least one of cellulose and hemicellulose, a saccharification enzyme, silica or a silica-containing substance, and at least one compound (A) selected from the group made of thiourea, a thiourea derivative, an isothiourea derivative, and a salt of any of these.