A protein having a novel saccharide oxidase activity capable of being subjected to various uses is provided.The present invention provides a protein having the following physicochemical characteristics:(1) effect: oxidizing a saccharide to produce a saccharic acid;(2) substrate specificity: acting on glucose, maltotriose, maltose, galactose, maltotetraose, lactose, and cellobiose; and,(3) [Km value of glucose]/[Km value of maltose] ≤ 1.