To provide a steel cord produceable in excellent productivity, and capable of maintaining fretting wear resistance when used as a reinforcing element for a tire, and to provide a pneumatic radial tire using the steel cord.

The steel cord includes an n+m+1 layer-twisted structure comprising a core 1 composed of n (n=1-4) filaments 11, one layer of sheath 2 formed around the core 1 and composed of m [m=n+(2-6)] filaments 12, and a coiling wire 3 coiled around the outer periphery of the sheath 2. The elasticity is ≤90%, the twisted pitch p of the coiling wire 3 is 5.0-10.0 mm, and the carbon content of the steel material of the coiling wire 3 is 0.50-0.65%.