To accurately and quickly bore patternized holes in a workpiece by providing a plate having patternized holes, and holding a position of a vertical directional hole of this plate by a holding member so as to correspond to a position of a vertical directional hole of the workpiece.

A plate P in which patternized holes P1 to P4 are bored in response to a work position of a cross-sectional almost rectangular platelike workpiece, is prepared, and the plate P is held by a holding member so that a position of a vertical directional hole of this plate P corresponds to a position of a vertical directional hole of the workpiece. Next, the butt end of the workpiece of a placing stand is positioned by being brought into contact with a stopper member, and this workpiece is held by the holding member. Afterwards, a raising/lowering body is arranged on a moving body horizontally freely movable on a base on the work machine side, and an engaging member member 49 arranged on this raising/lowering body is engaged with the holes of the plate, and a movement of the raising/lowering body is checked, and in this condition, holes are bored in the workpiece by a drill by using the holes of this plate P.