To provide a driving device for a machine tool, which is capable of eliminating the disadvantages of a prior art and safely handling even small components, wherein the function of clamping a workpiece and the function of transmitting machine torque to a workpiece chuck are separated, the force of a traverse direction is eliminated as much as possible and the rotational mass of a driving body is reduced.

A driving body 1 includes two thin and long openings 7, the openings 7 are respectively provided on an axis passing through the tip of a prism-like workpiece holding portion 5, a prism-like end part 8 is provided, the corresponding shape pins of the follower device of a circular grinder are received by the end part and, thus, a spring portion is expanded.