Toothed belts are provided having a plurality of teeth portions (4) formed on a surface of a belt body rubber layer (3), in which a plurality of core strands (2) are buried in the longitudinal direction of the belt (1), and a tooth cloth (6) is coated on the surface of the teeth portions (4). The belt body rubber layer (3) comprises a rubber composition comprising a mixed polymer obtained by formulating a hydrogenated nitrile rubber and a polymer alloy into which zinc polymethacrylate is finely distributed in a hydrogenated nitrile rubber in a range of 80:20 to 5:95 parts by weight, and crosslinking by an organic peroxide.