To provide a method for manufacturing a driving belt capable of accurately cutting the side faces of the belt and decreasing scraps (cut waste) in a manufacturing process for the belt.

The present invention relates to the method for manufacturing the driving belt in which a compression rubber layer and an extension rubber layer are laminated and integrated so that a core wiring is placed between them, and the belt with a rectangular section is bias cut. The belt 70 with the rectangular section is hung over at least two shafts with large diameter parts 83a on both sides of a small diameter part so that the compression rubber layer 6 is pinched between the large diameter parts. At least one of the stretched side and the relaxed side of the belt is pushed by a push roll 85, and the side faces of the belt are pinched by guide rolls 87. While a tension is added to the belt to make the belt run, a cutter 9 is advanced in the bias direction along a cutting line (a) on the compression rubber layer pushed by the push roll 85, and is retreated along a returning path line b which is out of the cutting line (a) and is not brought into contact with the compression rubber layer.