Disclosed are: a novel protein having an endoglucanase activity, which is found in a basidiomycete (into which edible mushrooms are classified) and is user-friendly from a safety standpoint and the like； novel DNA encoding the protein； a vector carrying the DNA； a transformant harboring the vector； a method for producing a protein having an endoglucanase activity by using the transformant； a method for producing a sugar by using at least one member selected from a protein having an endoglucanase activity and a basidiomycete； a method for producing ethanol by using a sugar produced by the aforementioned method； a food, a feed and a detergent each comprising a protein having an endoglucanase activity； and a method for treating a cellulose-containing woven fabric by using a protein having an endoglucanase activity. The protein is characterized by being derived from a basidiomycete, having a molecular weight of 18 kDa as determined by SDS-PAGE, and having an endoglucanase activity.
