A vulcanizing bladder 3 comprises a first bladder 11 configured to contact with an inner circumferential surface of an unvulcanized tire (T) and a second bladder 12 arranged inside the first bladder 11. A first fluid G1 is to be supplied between the first bladder 11 and the second bladder 12, and a second fluid G2 is to be supplied to an inside of the second bladder 12. At least one of an inner circumferential surface 11s of the first bladder 11 and an outer circumferential surface 12s of the second bladder 12 is provided with a guide groove 31 extending in a tire axial direction through which the first fluid G1 can pass.