To provide a method for manufacturing a transmission belt such as a V-ribbed belt, a double-ribbed belt or the like which can recycle a scrap rubber, which has an excellent side pressure resistance and a reduced noise at a traveling time.

The method for manufacturing the transmission belt comprises a first step of molding a short fiber-oriented rubber sheet 18 in which short fibers are oriented in a widthwise direction, a second step of notching ribbed grooves 19 extended in a longitudinal direction on the sheet 18 by a pair of ultrasonic cutters 31 and fluffing the fibers 22 from surfaces of the grooves 19, a third step of winding a belt constituting member and the short fiber oriented rubber sheet 18 cut in a predetermined length on a cylindrical mold 50, molding a belt molding, and further winding a sheet-like rubber mold 55 so that a protruding part 56 of the mold 55 is engaged with the grooves 19 of the short fiber oriented rubber sheet, and a fourth step of vulcanizing the belt molding and finishing the molding to a belt sleeve.