A step portion for mounting a row bar is provided at a table stepping down from the face of the table, and by lowering a pair of hooks crossing over the step portion in its width direction, a row bar held by the hooks is mounted on the step portion. While interposing the row bar mounted on the step portion between a pair of hooks and a side face of the step portion, the side in longitudinal direction of the row bar and the bottom face thereof are butted to the bottom face and the standing up side face of the step portion to position two axes of the row bar among XYZ directions, successively, positioning of the row bar in one remaining direction along longitudinal direction of the row bar mounted on the step portion is performed by moving the table in the one remaining axial direction.