Abstract: A printed circuit board working machine includes a spindle which holds a cutting tool and is movable to bring the tool into contact with and away from a printed-circuit board to be worked. A device for pressing down the printed-circuit board comprises a support mechanism associated with the spindle of the working machine for relative movement thereto, a plurality of holding sections movably supported by the mechanism and a driving mechanism for the holding sections. The holding sections are formed with holes of different sizes, respectively. When working operation, after the support mechanism causes the holding sections to move away to a position free from interference with the tool, the driving mechanism moves the holding sections to align one of the through holes, corresponding to a size of the tool to be used, with the tool.