The present invention provides a novel L-glutamate oxidase, a gene encoding the enzyme, and a method for producing the enzyme. By use of a gene encoding the enzyme, L-glutamate oxidase can be readily prepared at low costs through a recombinant DNA technique. The novel L-glutamate oxidase has the following physicochemical properties: (A) action: catalyzing the following reaction: L-glutamic acid+O.sub.2+H.sub.2O.fwdarw..alpha.-ketoglutaric acid+H.sub.2O.sub.2+NH.sub.3; (B) substrate specificity: being specific to L-glutamic acid; (C) molecular weight and subunit structure: molecular weight as determined through SDS-polyacrylamide gel electrophoresis of 70,000.+-.6,000, molecular weight as determined through gel filtration of 140,000.+-.10,000, and being a dimer formed of the same subunits having a molecular weight of 70,000.+-.6,000; (D) optimum pH: around pH 6.0 to 8.5; (E) heat stability: being stable up to 60.degree. C. at a pH of 7.4 for 30 minutes; and (F) coenzyme: flavin adenine dinucleotide (FAD).