To enable arbitrary setting of a stacking position or an unstacking position, and extend design flexibility without using an under part space of a conveyance means.

The device is equipped with advance/retreat cylinders 26 which can hold and release a tray W by approaching and separating tray holders 13 each other, and lifting cylinders 24, 25 which can lift the tray holders 13 between a position I possible to hold the tray W on the conveyance conveyor 1 and a position III allowing the tray to pass on the conveyance conveyor 1 on both sides of the conveyance conveyor 1. By the advancing and retreating of the tray holders 13 with the advance/retreat cylinders 26 and the lifting operation of the holders 13 with the lifting cylinders 24, 25, the stacking operation holds the tray W from the position I and lifts it up to the position III, carries in the tray W with the conveyance conveyor 1, lowers the tray W from the position III, stacks it on the tray W, holds the stacked tray, lifts it to the position III again, and stacks it by repeating that.