PURPOSE: To automatically reclamp a pipe and to accurately perform the positioning without the deviation of a machining position at the time of reclamping a pipe by providing at least either a pipe clamp device or a pipe index device freely movably in the longitudinal direction of the pipe.

CONSTITUTION: A chuck 9 is unclamped and opened, releasing a pipe W. The X-axis carriage 19 is moved, so that the pipe W is moved by the quantity of a command from an NC device. Then, the chuck 9 is clamped, and a pipe clamp device 29 is unclamped. After that, the Z-axis carriage 21 is moved upward in the Z-axis direction to complete a series of reclamping operations. Thus, automation may be contrived by automatically reclamping the pipe W with the pipe clamp device 29. In addition, the accurate positioning is performed with no deviation of a machining position occurring at the time of reclamping the pipe W.