To eliminate wasteful consumption of a material by smoothly cutting a superposed printed circuit board without providing a discarded plate and rapidly carry out cutting work.

The superposed printed circuit board (40) superposed at a plurality of sheets is fixed to a table (11) and a cutting position of a rotation saw (25) is set to a midway position of superposing thickness of the superposed printed circuit board (40). In this state, the rotation saw (25) is relatively moved from one side to the other side of the superposed printed circuit board (40) while it is rotated in a downward shaving direction. Then, the cutting position of the rotation saw (25) is set to a position penetrating through the superposing thickness of the superposed printed circuit board (40). In this state, the rotation saw (25) is relatively moved from the other side to one side of the superposed printed circuit board (40) while it is rotated in the same direction.