To position a tensile element at the central part in the thickness direction of a transmission belt made of a resin in which the tensile element is embedded.

An apparatus for producing a resin composite for a transmission belt is equipped with a die 5 having a tensile element inserting port 51, a molten resin inflow port 52 and a discharge port 53, a molten resin feeder 6 feeding a molten resin from the molten resin inflow port of the die 5 to the die 5 and a cooling roller 7 receiving an unsolidified composite 10 of the tensile element 3 discharged from the discharge port 53 of the die 5 and an unsolidified resin in its peripheral direction to successively and continuously cool the same. In this case, protruded parts 71 supporting the tensile element 3 and resin sinking parts allowing the resin of the unsolidified composite 10 to sink under its own wt. between the tensile element 3 and the outer peripheral surface of the cooling roller 7 to cool and solidify the same are provided to the outer peripheral surface of the cooling roller 7.