To provide a method for bonding an ethylene-α-olefin rubber composition to a fiber cord by which the ethylene-α-olefin rubber composition can well be bonded to the fiber cord to be a center wire of a transmission belt.

This method is to bond an ethylene-α-olefin rubber composition to a fiber cord. Furthermore, the fiber cord is treated with a first treating liquid comprising an isocyanate compound or/and an epoxy compound and then treated with a second treating liquid of a resorinol-formalin-rubber latex containing an acrylonitrile-butadiene rubber latex. The resultant treated fiber cord is subsequently treated with a third treating liquid containing a vulcanizing agent added to a halogenated polymer and further vulcanized in contact with an unvulcanized rubber composition of an ethylene-α-olefin.