The invention is intended to provide a printed board wherein a stable soldering processing can be executed on the basis of weight distribution in the printed board, and storage as well as control can be implemented on the basis of the weight distribution, and a method of displaying the identification mark on the printed board. The shock absorber can have a sag position which can be adjustable. The hydraulic unit is smaller than a cross member movable area where the cross members move relative to the body frame as seen from the direction of middle axes of the cross members. The position of a point on the first optically active surface and the position of a point on the second optically active surface are referenced in a coordinate system fixed to the holding device.