Provided is a run-flat tire in which a higher compatibility between the riding comfort and the run-flat travel durability during normal travelling can be attained.Provided is a run-flat tire comprising a bead portion 1, a side wall portion 2, a tread portion 3, a carcass 4 composed of one or more carcass plies extending toroidally between the pair of bead portions to reinforce these portions, and a side reinforcing rubber layer 5 having a crescent cross-sectional shape arranged on the inside of the carcass at the side wall portion.The carcass ply cord is a hybrid cord formed by twisting a filament composed of cellulose fibers and a filament composed of nylon, the thermal shrinkage stress (cN/dtex) of the hybrid cord at 177° C. after an adhesive treatment is not less than 0.20 cN/dtex, and the thermal shrinkage stress (cN/dtex) of the hybrid cord at 177° C. drawn from a tire product is not less than 0.10 cN/dtex.