To provide a method of manufacturing a power transmitting belt which eliminates the occurrence of a scrap such as a cut scrap, a ground scrap and a polished scrap, prevents a pin hole from occurring in the vicinity of an interface between a cog crest part of a compression rubber layer and an adhesive rubber layer, and prevents the occurrence of a crack in an early stage when a belt travels.

After reinforced cloth 40 served as the compression rubber layer and a sheet 55 for a compression rubber are wound around a molding die 41 reciprocally provided with a protrusion part and a ditch part, a jacket 57 provided with a communication ditch 63 on an inner peripheral face is covered to press it under heating, an unvulcanized sleeve 60 having a cog part is formed, a material providing at least a core wire and an extended rubber layer is wound around the back face of this sleeve 60 in turn to make a belt molding, and then this belt molding is thermally pressed, vulcanized and molded.