A pneumatic tire in which a plurality of circumferential main grooves (12, 13, 14) are formed in a tread surface at intervals in a tire width direction, which is partitioned into a plurality of land sections (21, 22, 23, 24) by the circumferential main grooves (12, 13, 14), and in which shoulder land sections are located at both sides of the plurality of land sections (21, 22, 23, 24) in the tire width direction, wherein: block segment sections, in which a plurality of L-shaped grooves having horizontal groove sections which extend in the tire width direction, inner end portions of which are coupled to one of the circumferential main grooves (12, 13, 14), and outer end portions of the horizontal groove sections terminate in a shoulder land section and vertical groove sections which extend in a tire circumferential direction, in each L-shaped groove an end portion of the vertical groove section at one side in the tire circumferential direction communicates with the outer end portion of the respective horizontal groove section via a first communicating section, are formed to be arranged in the tire circumferential direction and are partitioned by the L-shaped grooves adjacent to each other in the tire circumferential direction and said one of the circumferential main grooves (12, 13, 14); and outer rib-shaped sections which are located outward from the L-shaped grooves in the tire width direction and continuously extend in the tire circumferential direction are arranged at at least one side of the shoulder land sections, an end portion of the vertical groove section at the other side in the tire circumferential direction in each of the L-shaped grooves communicates with the horizontal groove section of another L-shaped groove of the L-shaped grooves, which is adjacent to the said each of the L-shaped grooves in the tire circumferential direction, via a second communicating section, and positions of the first communicating sections and the second communicating sections in the tire width direction are different from each other, characterized in that coupling sections configured to couple the block segment sections adjacent to each other in the tire circumferential direction are formed in the horizontal groove sections wherein the coupling sections are located at the inner end portions of the horizontal groove sections, and an outer circumferential surface of each of the coupling sections extends inward in the tire radial direction as it goes from an outer circumferential surface of one of the block segment sections toward another block segment section of the block segment sections, which is adjacent to said one of the block segment sections in the tire circumferential direction. block segment sections, in which a plurality of L-shaped grooves having horizontal groove sections which extend in the tire width direction, inner end portions of which are coupled to one of the circumferential main grooves (12, 13, 14), and outer end portions of the horizontal groove sections terminate in a shoulder land section and vertical groove sections which extend in a tire circumferential direction, in each L-shaped groove an end portion of the vertical groove section at one side in the tire circumferential direction communicates with the outer end portion of the respective horizontal groove section via a first communicating section, are formed to be arranged in the tire circumferential direction and are partitioned by the L-shaped grooves adjacent to each other in the tire circumferential direction and said one of the circumferential main grooves (12, 13, 14); and outer rib-shaped sections which are located outward from the L-shaped grooves in the tire width direction and continuously extend in the tire circumferential direction are arranged at at least one side of the shoulder land sections, an end portion of the vertical groove section at the other side in the tire circumferential direction in each of the L-shaped grooves communicates with the horizontal groove section of another L-shaped groove of the L-shaped grooves, which is adjacent to the said each of the L-shaped grooves in the tire circumferential direction, via a second communicating section, and positions of the first communicating sections and the second communicating sections in the tire width direction are different from each other, characterized in that coupling sections configured to couple the block segment sections adjacent to each other in the tire circumferential direction are formed in the horizontal groove sections wherein the coupling sections are located at the inner end portions of the horizontal groove sections, and an outer circumferential surface of each of the coupling sections extends inward in the tire radial direction as it goes from an outer circumferential surface of one of the block segment sections toward another block segment section of the block segment sections, which is adjacent to said one of the block segment sections in the tire circumferential direction.