The shell of this helical broach (1) is formed by stacking a plurality of wafer shells (20.sub.W(1)-20.sub.W(N)) in the axial direction, and is obtained by forming on the wafer shells (20.sub.W(1)-20.sub.W(N)) finishing blades (30.sub.W(1)-30.sub.W(N)) corresponding to teeth grooves on a piece to be cut (W) and forming the finishing blades (30.sub.W(1)-30.sub.W(N)) such that the blade width gradually increases with each of the aforementioned wafer shells (20.sub.W(1)-20.sub.W(N)) from the leading end of the cutting direction toward the trailing end of the cutting direction.

A turn broach machine may include a machining member machining a target to be cut; and an adaptor which is provided under the machining member, supports the machining member, and adjusts a position of the machining member. At the time of adjusting a position of a segment of the machining member from a plate provided in an adapter, the segment moves on an adjusting plate that is mechanically defined, such that work accuracy may be improved to increase marketability and a work time may be decreased to improve work convenience and productivity.