A method of saccharification and separation for plant fiber materials is provided. The method includes hydrolyzing cellulose contained in the plant fiber materials using a cluster acid catalyst in a pseudo-molten state to produce saccharide. The method further includes a first separation step of separating a mixture containing an aqueous saccharide solution in which at least a portion of the saccharide produced is dissolved, a cluster acid organic solvent solution, and residues into a solid content containing the residues and a liquid content containing the aqueous saccharide solution and the cluster acid catalyst solvent solution. The method further includes a second separation step of dehydrating the liquid content by a dehydration means capable of absorbing water through chemical absorption to deposit the saccharide in the aqueous saccharide solution, and separating a solid content containing the saccharide from a liquid content containing the cluster acid catalyst and the organic solvent.