The purpose of the present invention is to provide: an L-arginine oxidase that has high substrate specificity to L-arginine and can be used in an enzymatic measurement method capable of specifically measuring the L-arginine within a biological sample even when other amino acids are present, as is the case with samples that contain a variety of amino acids; an enzymatic measurement method for L-arginine which uses the oxidase; a measurement kit that can be used when implementing the enzymatic measurement method; an enzyme sensor that can be used in the enzymatic measurement method; and a novel microorganism that produces the L-arginine oxidase. The L-arginine oxidase according to the present invention is characterized by having a prescribed amino acid sequence, and by having high substrate specificity to L-arginine.
