PURPOSE: To conduct processing for which a tool is used together with the other tool by an exchange of the tools, by a method wherein automation of high-precision processing by a chain blade becomes possible by fitting easily a numerical control type machine tool such as a machining center with the chain blade.

CONSTITUTION: An upper housing 2 is fitted turnably freely with a shank 4 for connection with a main spindle of a machine tool and a locking pin 5 for positioning a chain saw l by connecting with the machine tool is formed further. The locking pin 5 performs function also which prevents turning-together of the housings 2, 3 from being performed when the chain saw 1 is operated. Since the housings 2, 3 are fitted to the machine tool under a state which is incapable of turning and a chain blade is turned and driven by driving the machine tool, automation of high-precision processing by a chain blade 6 can be performed by making use of the machine tool. Since the chain blades 6 are wound around an extension line of the central line of the shank 4, moment centering around the center of the shank 4 by reaction force at the time of cutting-off of a work is not generated.