The present invention relates to a bicycle frame molding device using a double blowing method, in which air is supplied from both sides of a tube that is used to manufacture parts related to a bicycle frame such as a frame, a handle bar, and a fork so that the air is injected with rapidity, the operation speed is improved, the air is uniformly distributed in the tube, high molding pressure is maintained in a mold, and product quality is improved. The bicycle frame molding device includes a pair of nozzles that are provided on both sides with a structure where air is supplied and discharged; the tube that is fixed in close contact with a discharge side of each of the nozzles on both sides to be expanded when supplied with the air from both of the sides; and an upper mold and a lower mold where molding grooves are formed to correspond to respective upper and lower surfaces of the tube with a nozzle fixing means formed in both side portions of the molding grooves, a frame manufacturing sheet, which is press-molded due to the expansion of the tube, being provided to be stacked in the molding groove.