Provided is (+)-5-(3,4-difluorophenyl)-5-[(3-methyl-2-oxopyridin-1(2H)-yl)methyl]imidazolidine-2,4-dione or a salt thereof, a selective TACE inhibitor and its use in the treatment of conditions caused by the excessive production and secretion of TNF-α. Also provided is a drug containing as the active ingredient (+)-5-(3,4-difluorophenyl)-5-[(3-methyl-2-oxopyridin-1(2H)-yl)methyl]imidazolidine-2,4-dione or a salt thereof.