PURPOSE: To simplify the structure of a numerical control machine tool and reduce its manufacturing cost by indexing its cutter holder with use of an NC shaft.

CONSTITUTION: A numerical control machine tool is provided with a saddle 1 travelling in parallel to a main shaft line on a bed, and a cross slide 2 moving on said saddle perpendicularly to the main shaft line, and a vertical indexing shaft 3 is provided on this cross slide 2 with respect to the travelling surface of said slide. Further, a supporting bench 4 is provided on the shaft 3, on said bench 4 a horizontal indexing shaft 6 is horizontally provided for indexing a turret cutter holder 5. Moreover, plural fixed tools and turning tools are removably mounted on the cutter holder 5, which is turned in a plane vertical to said shaft 6 by means of this shaft to index a prescribed tool at an arbitrary angle. Therefor, the shaft 6 is formed in an NC shaft. Thus, it is possible to simplify the structure of this machine tool and to reduce manufacturing cost.