A polynucleotide encoding a protein as defined in the following (a), (b) or (c): (a) a protein comprising the amino acid sequence as shown in SEQ ID NO: 2; (b) a protein comprising the amino acid sequence as shown in SEQ ID NO: 2 with one or several amino acids substituted, deleted, inserted or added, and having a tannase activity; (c) a protein comprising an amino acid sequence showing 90% or more homology to the amino acid sequence as shown in SEQ ID NO: 2, and having a tannase activity.