A run-flat tire, comprising: a tread portion; a plurality of blocks defined in the tread portion by a plurality of main grooves and a plurality of lug grooves formed in the tread portion; a plurality of sipes formed in the plurality of blocks to extend in a tire width direction; a sidewall portion disposed on both sides in the tire width direction of the tread portion; a belt layer disposed in the tread portion; a belt reinforcing layer disposed on an outer side in a tire radial direction of the belt layer; a tread rubber layer disposed on an outer side in the tire radial direction of the belt reinforcing layer in the tread portion; and a side reinforcing rubber disposed in the sidewall portion, the belt reinforcing layer comprising a center reinforcing portion, which is a portion in which more belt reinforcing layers are stacked at a position of a center region (Ac), which is a region in the tire width direction where the center block is located, than at positions other than the center region (Ac), characterized in that a density in a tire circumferential direction of the plurality of sipes formed in a center block which is the block closest to a tire equatorial plane among the plurality of blocks being larger than a density in the tire circumferential direction of the plurality of sipes formed in shoulder blocks which are the blocks located on outermost sides in the tire width direction, a density in the tire circumferential direction of the plurality of sipes formed in the center blocks being within a range from 0.10 sipes/mm or greater to 0.30 sipes/mm or smaller, a width in the tire width direction of the center block being within a range from 7% or greater to 20% or smaller of a development width of the tread portion, a width Wc in the tire width direction of the center reinforcing portion of the belt reinforcing layer being at any position in the tire circumferential direction within a range of 0.5 Gr ≤ Wc ≤ 2.5 Gr with respect to a thickness Gr of the side reinforcing rubber at a tire maximum width position, and an average width of the width Wc of the center reinforcing portion being within a range from 50% or greater to 90% or smaller of a width in the tire width direction of the center block. a tread portion; a plurality of blocks defined in the tread portion by a plurality of main grooves and a plurality of lug grooves formed in the tread portion; a plurality of sipes formed in the plurality of blocks to extend in a tire width direction; a sidewall portion disposed on both sides in the tire width direction of the tread portion; a belt layer disposed in the tread portion; a belt reinforcing layer disposed on an outer side in a tire radial direction of the belt layer; a tread rubber layer disposed on an outer side in the tire radial direction of the belt reinforcing layer in the tread portion; and a side reinforcing rubber disposed in the sidewall portion, the belt reinforcing layer comprising a center reinforcing portion, which is a portion in which more belt reinforcing layers are stacked at a position of a center region (Ac), which is a region in the tire width direction where the center block is located, than at positions other than the center region (Ac), characterized in that a density in a tire circumferential direction of the plurality of sipes formed in a center block which is the block closest to a tire equatorial plane among the plurality of blocks being larger than a density in the tire circumferential direction of the plurality of sipes formed in shoulder blocks which are the blocks located on outermost sides in the tire width direction, a density in the tire circumferential direction of the plurality of sipes formed in the center blocks being within a range from 0.10 sipes/mm or greater to 0.30 sipes/mm or smaller, a width in the tire width direction of the center block being within a range from 7% or greater to 20% or smaller of a development width of the tread portion, a width Wc in the tire width direction of the center reinforcing portion of the belt reinforcing layer being at any position in the tire circumferential direction within a range of 0.5 Gr ≤ Wc ≤ 2.5 Gr with respect to a thickness Gr of the side reinforcing rubber at a tire maximum width position, and an average width of the width Wc of the center reinforcing portion being within a range from 50% or greater to 90% or smaller of a width in the tire width direction of the center block.