Provided are a apparatus and a method for vulcanizing a pneumatic tire, where are capable of: smoothly releasing a vulcanized pneumatic tire from multiple sectors separated from one another in a circumferential direction in each of an upper mold and a lower mold; and thereby lightening load on each mold. In addition to springs for biasing the sectors to always move into a smaller diameter, respectively, pushpins for moving the sectors into larger and smaller diameters are actuated by the respective cylinder rods of drive cylinders, and thereby the movements of the individual sectors into the larger and smaller diameters are controlled. Accordingly, even though the sectors would otherwise move abruptly into the smaller diameter due to biasing forces of the springs after the vulcanized tire is released from the sectors at the larger diameter, a radius-reducing movement speed of the sectors is control led by the cylinder rods in contact with rear ends of the push pins.