PURPOSE: To obtain smooth take-in and take-out of pallet by arranging pallet transfer trucks and truck receiving and delivering forks in a loop shape from the setting position of a matter to be processed to the conveying truck and from a conveying truck of a processed matter to a conveying outlet.

CONSTITUTION: A pallet 25 which is set a work to be processed at the position of A or B is loaded on a truck 1 and conveyed to the C position, and a fork 5 on a conveying truck 3 conveys the pallet 25 on the truck 3. The truck 3 runs on a rail 6 to supply the work to a processing machine and the truck 1 is returned to the A position and prepares next operation. The conveying truck 3 loads a pallet which is set a processed work and returns on the rail 6, and conveys the pallet to the D position by the fork 5. Then a fork 9 on a truck 7 loads the pallet 25 on the truck 7 and moves on the rail 19 to the G position. Here the work is removed and taken out. Next the fork 9 carries the pallet 25 to a cleaning station 13, and the cleaned pallet is carried by a fork 15 to the position of A or B. Thus, the operation can smoothly be repeated.