The present invention provides a novel glucose dehydrogenase that has excellent substrate specificity and that is suitable for use in SMBG. The present invention provides a flavin-bound glucose dehydrogenase having the following characteristics (1) to (5): (1) Temperature stability: stable at a temperature of 45° C. or lower; (2) stable at a pH range of 4.5 to 7.5; (3) substrate specificity: the reactivity to D-xylose, maltose, or D-galactose is 2% or less, based on the reactivity to D-glucose taken as 100%; (4) optimal activity temperature: 34 to 47° C.; and (5) optimal activity pH: 6.3 to 6.7.
