is formed along the shape of the top faces 5a and the grooves 5b of the internal die 4 then the elastomer material is hardened and hereafter the forming die 7 is disconnected deriving a cylindrically shaped body of a power transmission belt the power transmission belt a is obtained by slicing roundly through the cylindrical body with a predetermined width as per the standard process a bulky polyester nonwoven fabric 3 whose weight per unit area is 70 gr m 2 and whose full thickness under non pressure is 1 mm was needle punched and not done with adhesion treatment the outer circumference of the internal die 4 for forming a timing belt whose diameter was about 155 mm was covered softly therewith so that almost no pressure was applied thereto then the tensile cords 2 made by dupont co the trade name of which is 34 kevlar 34 composed of aromatic polymide were wound spirally thereon with a constant tension so that the nonwoven fabric 3 should be 0 1 mm in thickness h at the top faces 5a of the internal die 4 for forming the tooth bottoms 1a in this process the nonwoven fabric 3 was as shown in fig3 compressed to be 0 1 mm in thickness on the top faces 5a and stuffed softly into the grooves 5b that are 1 2.