Method of making a vacuum vessel

A method of making a vacuum vessel including a pair of plates including a face plate and a rear plate bonded to each other using a bonding member, the method comprising:

• applying the bonding member to a periphery of at least one of the face plate and the rear plate;
• placing the pair of plates, to at least one of which the bonding member has been applied, in contact with each other through the bonding member disposed therebetween at a temperature lower than the melting point of the bonding member;
• fastening parts of sides of the pair of plates, which have been placed in contact with each other, to each other using a positioning jig made of bimetal;
• separating the pair of plates, the parts of sides of which have been fastened to each other, from each other by placing the pair of plates in an atmosphere having a pressure lower than atmospheric pressure and by thermally deforming the positioning jig by performing heating to a first temperature equal to or higher than the melting point of the bonding member;
• and
• fixing the pair of plates to each other around the entire peripheries thereof using the bonding member by performing cooling from the first temperature so as to reduce thermal deformation of the positioning jig and by making the pair of plates, which have been separated from each other, contact each other through the bonding member disposed therebetween.