PURPOSE: To reduce the number of working stations thus to reduce the installation space by performing same work in the downstream while feeding the products to be worked through reverse feed conveyor to the working station in the upstream.

CONSTITUTION: A reverse feed conveyor 11 parallel with a carry conveyor 1 will run in reverse direction. The working station 12l is communicated through carry-in path (a) and carry-out path (b) with the conveyor 1 while through carry-in path (c) with the conveyor 11. The products to be worked carried over the conveyor 1 are carried through carry-in path (a) into the working station 12l for the section l to execute working thereafter carried out through carry-out path (b) onto the conveyor 1 to be carried out to the downstream. Then they are carried through the carry-in path (a) into the working station 12M for the section M and worked thereafter carried through carry-out path (d) onto the conveyor 11 to be carried to the upstream and carried through carry-in path (c) to the working station 12L for the section L and to execute similar working.