A tray handling apparatus comprises a plurality of guides, a chuck device, a linear movement device, and a rack and pinion device. A space defined by the erected guides is used to hold a tray stack. The chuck of the chuck device is located at the center position of the bottom area of the space. The linear movement device is used to move the chuck relative to the guides. The rack and pinion device is used to cause the guides to move symmetrically. When an operator moves any one of the guides, the other guides move symmetrically and the center of the bottom area of the space surrounded by the guides remains at the same location during the movement of the guides. The operator does not need to adjust the position of the chuck if the positions of the guides are changed.