PURPOSE: To produce a steel cord for rubber reinforcement, having a simple structure at low cost, capable of efficiently manifesting ultra-high mechanical strength at least comparable to those of conventional cords composed of four wires, also excellent in both corrosion resistance and rigidity, and high in flexural fatigue resistance despite being relatively larger in diameter of each of the wires.

CONSTITUTION: By using a wire made of a carbon steel wire 0.80-0.89wt.% in carbon content, having tensile strength satisfying the relationship: Y≥-200d+400, and <7% in the torque drop-off when subjected to such a twisting-torque test as to apply one-way torsion followed by reverse torsion to a specimen, two of such wire are bundled in nearly parallel with each other and a single wire is spirally wrapped around the resultant bundle at a pitch of 45-65 times the diameter of this wire, thus obtaining the objective steel cord.