A toothed belt of the present invention comprises a back surface section (1) and tooth sections (2) that are made of an acrylonitrile-butadiene copolymer (NBR) with a hydrogenation rate of 90% or more; a tooth cloth (3) that covers the surface of the tooth sections and tooth lands, the tooth cloth being made of an industrial nylon raw fiber with a viscosity relative to sulfuric acid of 2.45 to 2.53, a tensile strength of 5 g/denier or more, and a fineness of single fibers of 5 denier or less and being treated with resorcinol-formaldehyde-latex (RFL) liquid in which resorcinol-formaldehyde resin is mixed with a hydrogenated NBR as a latex component; and core fibers (4) with a core diameter of 0.63 to 0.85 mm, the core fibers being made of twisted bundles of glass fibers of high strength. <IMAGE>
