A tire forming mold has a side mold portion and an annular mold portion fitted to an outer side in a tire diametrical direction of the side mold portion at a time of clamping the mold, wherein the annular mold portion is constructed by a combination of sectors which are divided in a tire circumferential direction, and each of the sectors is capable of displacing in the tire diametrical direction, wherein a fitting diameter of the annular mold portion is set to be equal to or more than a fitting diameter of the pair of side mold portions, an annular rubber introduction groove extending along the tire circumferential direction is provided at least in one of a fitting surface of the annular mold portion and a fitting surface of the pair of side mold portions, and a shallow groove portion is formed in an introduction port of the rubber introduction groove.