To provide a method for modifying a rubber material-reinforcing cord, performed together with the immersion into an adhesive liquid and capable of further high-efficiently, performing the modification of the cord and a modified rubber material-reinforcing cord obtained therefrom.

This method for modifying the rubber material-reinforcing cord comprises an immersion treatment process for immersion-treating an organic fiber cord 1 as a rubber material-reinforcing cord with the adhesive liquid 14 and a heat-treating process of performing a laser beam irradiation from in a plurality of laser light sources 20 toward the rubber material-reinforcing cord 1. The modified rubber material-reinforcing cord obtained by the above modification method shows 2-4% intermediate elongation at 4×10-2 N/dtex.