A heavy duty pneumatic radial tire comprises a radial carcass, a belt and a tread, wherein the belt is comprised of four or more belt layers, cords of adjacent two belt layers among these layers are crossed with each other with respect to an equatorial plane of the tire. In this tire, when a main cross belt is constituted with a widest-width belt layer and a wider-width belt layer in two belt layers adjacent to the widest-width belt layer, an inclination angle of cords in a neighboring narrower-width belt layer arranged at an outside of the main cross belt in the radial direction and adjacent thereto with respect to an equatorial plane of the tire is made larger than an inclination angle of cords in a belt layer arranged outward in the radial direction among the widest-width and wider-width belt layers.