An object of the present invention is to provide a more practically advantageous enzyme usable as a reagent for measuring blood glucose than the known enzymes used as blood glucose sensors.A modified flavin adenine dinucleotide dependent glucose dehydrogenase (FADGDH) with more improved heat stability than FADGDH derived from wild-type FADGDH, the modified FADGDH being derived from preferably a eukaryote, more preferably a filamentous fungus, and furthermore preferably an Aspergillus fungus, and, for example, those having a primary structure with at least one amino acid substituted, deleted, inserted or added to FADGDH having an amino acid sequence represented by SEQ ID Nos. 2 or 46 in the sequence table.