To provide a cutting method different from any of the conventional cutting methods, cutting round pipes and square pipes each having a square or rectangular cross section as well in the wide ranges of their sizes and thickness.

The cutting method constitutes a toggle joint with a pair of sliders moving on a linear track in a same direction and two link arms and provides a rotating blade at a pivot portion of the links, allowing the position of the rotating blade viewed from the center of a workpiece to be freely controlled and moved only by controlling the positions of the pair of sliders moving toward and away from each other. The cutting method cuts the workpiece with such rotating blades disposed on two opposite sides of the workpiece, or in four positions surrounding the workpiece.