To provide a synthetic fiber tire cord fabric for reinforcing rubber, which is capable of uniformly stretching weft yarns with the increase of a space among warp yarns when molding them into a circular ring form in a tire-molding process, and exhibiting an excellent effect for improving the uniformity of a pneumatic tire, and a pneumatic tire using the same.

This tire fabric for reinforcing the rubber, which is obtained by weaving warp yarns composed of the synthetic fibers having been subjected to the first twist and the final twist and the weft yarns composed of the synthetic fibers as the tire fabric, wherein the weft yarn consists of a core yarn and a sheath yarn, the core yarn contains monofilaments having a flatness expressed by the following formula of 1.5 and also the weft yarn has an elongation at break of 50%. The flatness=(the length of a longer axis of a cross section of the monofilament)/(the length of a shorter axis of the cross section of the monofilament).