To facilitate the centering of wire-guide nozzles in mounting on timing belts and to position precisely plural wire-guide nozzles within a short time.

This is a mounting jig 1 which is applied to timing belts and wire-guide nozzles under the temporarily attached condition to regulate the position of wire-guide nozzles before final attachment, and which is to be removed after the final fixing. It comprises a positioning member 4 having guide grooves to be engaged with belt cogs on its both ends contacting with two timing belts, and has a length d2 corresponding to the separation distance of the two timing belts. The jig is also provided with guide plates 5 having an opposition width h corresponding to the width of the wire-guide nozzle, fixed on both sides of the positioning member 4, and a pressure board 6 which retains by pinching between the positioning member 4 the wire-guide nozzle arranged between the guide plates 5 and at least one of the timing belts at the time of the final fixing, and which is supported attachable and detachable freely by the guide plates 5 so that this retention by pinching may be released after the final fixing.