To provide a pneumatic radial tire and a steel cord for rubber reinforcement that can be used for the tire for suppressing the occurrence of a separation trouble due to core removal of the steel cord while suppressing growth in an outer diameter.

In the pneumatic radial tire using a steel cord S of N+M construction including a core 10 formed by N steel filaments 11 twisted with each other, and a sheath 20 comprising M steel filaments 21 twisted around the core 10 in the same direction but different pitch from the core 10 as a reinforcement material of a tire constituent member, at least one line part 31 extending spirally is processed on the surface of at least one steel filament out of the steel filaments 11, 21 that constitutes the core 10 and the sheath 20 of the steel cord S.