A tool main spindle, whose cutting angle can be changed, is translated by an X-axis moving mechanism portion on an X-axis provided in a plane perpendicular to an axis of a work; and is translated on a Y-axis by a Y-axis moving mechanism portion. Cutting of the work is performed by setting the cutting angle of the tool main spindle to an angle of the cutting tool at which the work has large dynamic rigidity, and causing an axis of a cutting tool to cross the work axis, and cutting the work with the cutting tool toward the axis of the work by cooperatively operating the X-axis moving mechanism portion and the Y-axis moving mechanism portion.