To efficiently assemble or manufacture a belt by fastening a plurality of elements in a circular manner using a ring.
A pair of receiving members 23 and 26 for holding the ring 9 respectively comprises a first receiving face 37 to which the ring 9 is applied, and a second receiving face 28 which is formed outer circumferential side of the first receiving face 37 to hold the element 6 attached to the ring 9 therebetween. A thrust mechanism 30 is adapted to straighten a portion of the ring 9 between the receiving members 23 and 26 by moving at least one of the receiving members 23 and 26 away from the other receiving member thereby applying a tension to the ring 9, and to adjust a distance between the receiving members 23 and 26 thereby equalizing the tension being applied to the ring 9 in both of a case in which the ring 9 is applied to the receiving member 23 and 26 and a case in which the element 6 attached to the ring 9 is applied to the receiving member 23 and 26.