The present invention addresses the problem of providing a toothed belt excellent in durability of a tooth rubber portion.　As a solving means, provided is a toothed belt comprising: a belt body which comprises a back rubber portion having a flat belt shape and a plurality of tooth rubber portions provided to a surface on one side of the back rubber portion and which is formed from a rubber composition containing H-NBR as a main component; a core strand embedded in the back rubber portion; and a tooth reinforcement fabric which coats a surface on the side provided with the plurality of tooth rubber portions. The tooth reinforcement fabric uses aramid-based fibers as the warp yarns (yarns extending in the belt width direction) and uses, as the weft yarns (yarns extending in the belt circumferential direction), composite yarns made from polyurethane-based fibers as the core yarns and aramid-based fibers and woolly nylon fibers as the cover yarns.