PURPOSE: To enhance a cutting effect, by constituting a cutting tool mechanically holding single crystal diamond on a shank and using protrusions, provided in the single crystal diamond, successively as an edge point.

CONSTITUTION: A strip-shaped diamond single crystal, which contains nitrogen being left as synthesized, is prepared. All the eight faces of said single crystal are composed of faces (100), and a corner part of said faces has a small face (111). A holder is constituted such that a fixing jig 3, providing in one part of its bottom surface a recessed part 1, can be stopped by a thread on a shank 2. The strip-shaped diamond single crystal, which is placed in the recessed part 1 of the fixing jig 3, is held to be tightened by using a screw to a threaded hole 4. Here a small copper piece is arranged in the periphery of the single crystal for the purpose of more completely performing the tightening.