NOVELTY - A xylanase chosen from (a) protein exhibiting xylanase activity, comprising amino acid sequence in which e.g. amino acid residue at position 77 (alanine) is substituted by proline in SEQ ID NO: 2, (b) amino acid sequence exhibiting greater than or equal to 90% similarity, with respect to the SEQ ID NO: 2, and (c) amino acid sequence in which one or more amino acids at positions other than the substitution of the SEQ ID NO: 2 are deleted, substituted, or added, is new. Sequences not defined here may be found at ftp://ftp.wipo.int/pub/published_pct_sequences/publication.    USE - The xylanase is useful for preparing saccharide (claimed).    ADVANTAGE - The xylanase has excellent xylan decomposing activity at 50-60 degrees C, and 60% or more activity at 45-65 degrees C.    DETAILED DESCRIPTION - A xylanase chosen from (a) protein exhibiting xylanase activity, comprising amino acid sequence in which amino acid residue at position 77 (alanine) is substituted by proline, amino acid residue at position 212 (serine) is substituted by alanine, amino acid residue at position 214 (alanine) is substituted by proline, amino acid residue at position 217 (glutamine) is substituted by proline, amino acid residue at position 323 (serine) is substituted by asparagine, and amino acid residue at position 328 (alanine) is substituted by proline in SEQ ID NO: 2, (b) amino acid sequence exhibiting greater than or equal to 90% similarity, other than the substitutions with respect to the SEQ ID NO: 2, and (c) amino acid sequence in which one or more amino acids at positions other than the substitution of the SEQ ID NO: 2 are deleted, substituted, or added, is new. Sequences not defined here may be found at ftp://ftp.wipo.int/pub/published_pct_sequences/publication. INDEPENDENT CLAIMS are included for the following:    (1) gene encoding the above-mentioned xylanase;    (2) recombinant vector comprising the above-mentioned gene;    (3) transformant formed by transducing the recombinant vector into host;    (4) enzyme formulation for biomass saccharification comprising the xylanase; and    (5) method for preparing saccharide, involves performing saccharification process of biomass by the above-mentioned enzyme formulation.