To improve run flat durability while suppressing running resistance and noise.

The run flat tire 1 includes: a carcass 6 of a toroidal shape, which reaches the bead core 5 of a bead part 4 from a tread part 2 via a side wall part 3; a side reinforcement rubber layer 9 of a roughly crescent shape in a cross section, which is arranged inside the carcass 6 of the side wall part 3; and a side wall rubber 3G arranged in the outside of the carcass 6 of the side wall part 3 and forming a tire outer surface 3S. A slit 11 continuously extending to a tire circumferential direction is formed in the side wall rubber 3G. The slit 11 is closed in a normal load state in which a tire is rim-assembled to a normal rim J, the tire is filled with normal internal pressure, and the tire is loaded with a normal load. It is opened in the run flat state in which the internal pressure is zero, and to which the normal load is applied.