A thermal processing station is provided with a first conveyor that conveys a wafer from a first conveyor access portion and a second conveyor that conveys another wafer from a second conveyor access opening portion. The wafer conveyed from the first conveyor is conveyed along a route consisting of the second conveyor, a washing portion, the second conveyor again, the first conveyor, and a thermal processing portion. On the other hand, the wafer conveyed from the second conveyor is conveyed along a route consisting of the washing portion, the second conveyor again, the first conveyor, and the thermal processing portion. An intermediate transfer portion that is free to rotate and rise and lower is provided between the first and second conveyor. A control section does not rotate the intermediate transfer portion while the wafer is being transferred along the former route, but it does rotate the intermediate transfer portion through 180.degree. for the latter route, to keep the orientation of wafers constant during the thermal processing. In this manner, the orientation of objects to be processed, such as semiconductor wafers, can be easily managed during thermal processing.