In an alignment stocker having an opening and plural shelf members, metal rings are pushed between the plural shelf members. The meta rings are deformed into an approximately polygonal shape to pass through the opening, in an arranged State of the metal rings, by pressing and holding from insides thereof, and are extracted from the opening. Using a heat treatment jig, which has the same opening as that of the shelf member and enables the metal rings to be mounted parallel to each other in a vertical direction and to be spaced the predetermined interval from each other, the metal rings held from the insides thereof in the arranged state, are inserted from the opening of the heat treatment jig into the heat treatment jig, are mounted in the heat treatment jig by releasing the inside holding, and then are heated and extracted from the shelf members.