In a conventional conveyor line, an empty specimen rack conveyor line is provided separately from a specimen rack conveyor line having a specimen mounted thereon. However, crossing of the conveyor lines leads to the decrease in processing speed. Also, when a specimen rack conveyor line and an empty specimen rack conveyor line are configured on two stages, a vertical movement mechanism needs to be added in order to connect the upper-stage conveyor line and the lower-stage conveyor line, and there is a possibility that the system is complicated and the cost thereof is increased. In the present invention, by connecting an empty holder conveyor line and a main conveyor line disposed up and down on two stages via one conveyor line having a horizontal part and an inclined part, crossing of the conveyor lines can be eliminated and an inexpensive structure can be achieved.