This invention relates to a pneumatic radial tire being excellent in steering stabilities during low-speed running and high-speed running, and more particularly to a pneumatic radial tire comprising at least one belt reinforcing layer 6A, 6B disposed on a belt 5 outward in a radial direction of the tire, characterized in that a reinforcing element constituting the belt reinforcing layer 6A, 6B is a polyketone fiber cord satisfying conditions of the following equations (I) and (II): σ≧−0.01×E+1.2  (I) σ≧−0.02  (II) [wherein σ is a thermal shrinkage stress (cN/dtex) at 177° C.; and E is an elastic modulus (cN/dtex) at 25° C. under a load of 49 N].