To provide a pneumatic tire reducing pattern noise caused by lug grooves of a tread part by generating axle force in a direction opposite to fluctuation of tire axle force generated by the lug grooves.

Rib grooves 12 extending in a tire circumferential direction X and the lug grooves 13 extending in a tire width direction Y with appropriate intervals in a circumferential direction of a rib row B formed by the rib grooves 12 are formed on a tread surface part T of the tread part 11, and a plurality of blocks 14 are formed by the rib grooves 12 and the lug grooves 13. By providing rigidity increased portions 20 canceling out a reduced amount of the tire axle force generated by the lug grooves 13 on surfaces of the blocks 14, exciting force of an axle is reduced, and the pattern noise caused by it is effectively reduced.