PURPOSE: To traverse the halfway of a manufacture line by integrally constituting partly a specific section of a return feed conveyer and a supply conveyer made removable from a circulating route.

CONSTITUTION: An intermediate unit 10 of integrally forming at least partly a specific section 6c of a return feed conveyer 6 and partly a specific section 7c of a supply conveyer 7 in a pair of reciprocating conveying routes, constituted of the return feed conveyer 6 and the supply conveyer 7, is provided. This intermediate unit 10 is constituted removably from a circulating route, and in the case of work by an attendant necessary for traversing the halfway of an electronic parts mounting system line, by removing the intermediate unit 10 from the circulating route, a passage for work is ensured on the halfway of the electronic parts mounting system line.