A pneumatic tire 10, in which at least one rib groove 12 extended in a tire circumferential direction is formed on a tread surface portion T of a tread portion 11, and portions 13 discontinuous in terms of rigidity are formed in a circumferential direction of rib lines B formed by the rib groove 12, the discontinuous portions 13 causing variations of tire axle force. Rigidity changing portions 20 which cancel the variations of the tire axle force are provided in the rib groove 12, the variations being caused by the discontinuous portions 13. Thus, vibrational force to an axle is lowered, and pattern noise caused thereby is reduced effectively.