A tire vulcanization bladder assembly is manufactured by placing a first ring part on a base stage installed on leg parts in a periphery of a first end opening of a bladder; sandwiching a first clamp part of the bladder, the bladder being in an upright position with the first clamp part on a lower side and a second clamp part located in a periphery of a second end opening of the bladder on an upper side, by the first ring part, thereby attaching the first ring part to the bladder; inserting an inside ring member of a second ring part into the bladder from above on an inside ring member of the first ring part; moving the inside ring member of the second ring part upward relative to the bladder to a position of the second clamp part; and attaching the second ring part to the second clamp part.