A tire vulcanizing device including: an upper annular mold attaching member and a lower annular mold attaching member that respectively attach side portion forming molds for forming side portions of a tire; a plurality of segments that respectively attach a plurality of segmented tread molds for forming a tread portion of the tire; and a mold closing mechanism for radially moving the segments to close the tread molds at an advanced end. The respective segments are respectively independently provided with heat medium passages for applying heat for vulcanization to the tread molds when supplied with a heat medium.