Abstract: A method for the determination of 1,5-anhydroglucitol, characterized by using any one of the following proteins (a) to (c): (a) a protein which comprises an amino acid sequence depicted in SEQ ID NO:2; (b) a protein which comprises an amino acid sequence having the deletion, substitution and/or addition of one or several amino acid residues in the amino acid sequence depicted in SEQ ID NO:2 and which has a sorbose dehydrogenase activity; and (c) a protein which comprises an amino acid sequence having at least 60% sequence homology to the amino acid sequence depicted in SEQ ID NO:2 and which has a sorbose dehydrogenase activity.