PURPOSE: To achieve smooth circulation of pallet trays on which works are loaded in a horizontal direction by installing one or more pallet trays on the first and the second rails, and installing the pallet trays on the first and the second rails forming a circle.

CONSTITUTION: Moving pieces 46 are engaged with protruding pieces of a pallet tray 4 by driving cylinder devices 38, 40, 42, 44 in one direction consecutively. The driving force is applied to the pallet tray 4 to move the pallet tray 4 on rollers of a center rail 8 and a side rail 10 smoothly. As a result, this arrangement allows the pallet tray 4 to be circulated along a circulating passage 6 without generating falling or displacement of smaller works, and also allows the works to be transferred in a stable manner.