NOVELTY - A thermostable cellobiohydrolase having cellobiohydrolase catalytic region and exhibiting cellobiohydrolase activity under condition of at least 75 degrees C and 5.5 pH, is new. The cellobiohydrolase catalytic region includes polypeptide comprising an amino acid sequence of SEQ ID NO: 1, 3, 5 or 7, or polypeptide comprising an amino acid sequence obtained by deleting, substituting or adding one or more amino acid residues in the amino acid sequence of SEQ ID NO: 1, 3, 5 or 7.    USE - The cellobiohydrolase is useful in cellulase mixture which is used for preparing degradation products of cellulose (all claimed) contained in plant biomass including bioethanol and biofuel.    ADVANTAGE - The cellobiohydrolase is thermostable, and hence is suitable for saccharification of cellulose even under high temperature conditions.    DETAILED DESCRIPTION - A thermostable cellobiohydrolase having cellobiohydrolase catalytic region and exhibiting cellobiohydrolase activity under condition of at least 75 degrees C and 5.5 pH, is new. The cellobiohydrolase catalytic region comprises (a) polypeptide (P1) comprising an amino acid sequence of SEQ ID NO: 1, 3, 5 or 7, (b) polypeptide (P2) comprising an amino acid sequence obtained by deleting, substituting or adding one or more amino acid residues in the amino acid sequence of SEQ ID NO: 1, 3, 5 or 7, or (c) polypeptide (P3) comprising an amino acid sequence exhibiting 80-100% sequence identity to the amino acid sequence of SEQ ID NO: 1, 3, 5 or 7. INDEPENDENT CLAIMS are included for the following:    (1) polynucleotide having region that encodes the above-mentioned cellobiohydrolase catalytic region, where the region comprises base pair sequence encoding the above-mentioned polypeptide (P1), (P2) or (P3) having (a) base pair sequence of SEQ ID NO: 2, 4, 6, or 8 respectively, (B) base pair sequence exhibiting 80-100% sequence identity to the base pair sequence of SEQ ID NO: 2, 4, 6, or 8, or (c) base pair sequence capable of hybridizing with the base pair sequence of SEQ ID NO: 2, 4, 6, or 8 under stringent conditions;    (2) host cell comprising expression vector integrated with the above-mentioned polynucleotide, where the vector express the polypeptide having cellobiohydrolase activity under condition of at least 75 degrees C and 5.5 pH;    (3) transformant obtained by introducing the above-mentioned expression vector;    (4) preparation method (M1) of the above-mentioned thermostable cellobiohydrolase;    (5) cellulase mixture comprising the above-mentioned thermostable cellobiohydrolase and at least one of other cellulase;    (6) method (M2) for preparing cellulose degradation product, involves contacting material containing cellulose with the above-mentioned thermostable cellobiohydrolase or transformant;    (7) method (M3) for preparing polynucleotide encoding the thermostable cellobiohydrolase, involves taking organism derived DNA or reverse transcribed RNA as template, amplifying the template by PCR using primers comprising forward primer and reverse primer, where the forward primer comprises a base pair sequence of SEQ ID NO: 12 or a base pair sequence obtained by adding one or more base pair residues at 5'-terminal of the base pair sequence of SEQ ID NO: 12, and reverse primer comprises a base pair sequence of SEQ ID NO: 13 or a base pair sequence obtained by adding one or more base pair residues at 5'-terminal of the base pair sequence of SEQ ID NO: 13, and obtaining polynucleotide having base pair sequence encoding the cellobiohydrolase as amplified product;    (8) primer comprising a base pair sequence of SEQ ID NO: 12 or a base pair sequence obtained by adding one or more base pair residues at 5'-terminal of the base pair sequence of SEQ ID NO: 12; and    (9) primer comprising a base pair sequence of SEQ ID NO: 13 or a base pair sequence obtained by adding one or more base pair residues at 5'-terminal of the base pair sequence of SEQ ID NO: 13.    5'-caccatgttggacaatccattcatcggag-3' (SEQ ID NO: 12), and 5'-ttagggttggatcggcggatag-3' (SEQ ID NO: 13). Sequences not defined here may be found at ftp://ftp.wipo.int/pub/published_pct_sequences/publication.