An upper metal mold clamp device in a tire vulcanizing machine of the type that an upper metal mold is detachably fixed to a bolster by rotating clamp rods vertically penetrating through the bolster and provided with clamp claws at their bottom ends, is improved. Drive units rotate the respective clamp rods independently of rotation of the other clamp rods. Nuts are mounted onto the bolster plate in an unrotatable but vertically movable manner, and threadedly engaged with male screws at the upper portions of the clamp rods. Hollow spaces for accommodating the clamp claws are formed around the clamp rods on the bottom surface of an upper heat plate held in contact with the upper metal mold.