A pneumatic radial tire 1 including a carcass 6 and a belt layer 7 is provided with a cord-reinforced layer 12 with reinforcing cords of organic fiber being disposed at angles of 30 to 60 degrees with respect to a tire circumferential direction at a buttress portion Bs thereof. A ply turnup portion 11 of the carcass 6 is terminated radially outside a tire maximum width point M. The cord-reinforced layer 12 is arranged such that its outer end portion in the radial direction 12U is pinched between the carcass 6 and the belt layer 7 and such that its radially inner end portion 12L is secured between the ply main portion 10 and the ply turnup portion 11 of the carcass 6.