To provide a method for manufacturing a transmission belt, capable of reducing noise in run of the belt, and reducing manufacturing manhours by uniformly attaching short fibers onto a transmission surface of the belt to be exposed in the surface.

The transmission belt is composed by laminating a rubber layer containing core wires embedded along the belt length, and a compression rubber layer having a molded part adjoining the rubber layer, comprising rib parts extended along the belt length or cog parts provided at a prescribed interval along the belt length laminated with it. This method comprises a process of winding at least the core wires 48 around a flexible jacket surface 42 of an inner die 41, and laminating an unvulcanized rubber sleeve 24 having the short fibers 26 planted on a surface layer 23 that has been baked to be finished to be a belt mould 25, and a process of disposing the inner die 41 to an outer die 46 having die parts 45 engraved in an inner circumferential surface, and expanding the flexible jacket 42 to tightly apply the belt mold 25 to the die parts engraved in the outer die to be then vulcanized for forming a belt sleeve 51.