PURPOSE: To enhance rigity of a CNC lathe and permit heavy cutting by keeping a distance between the moving axis of a Z-axis slider and the axis of a chuck constant with no relation to sizes or workpieces.

CONSTITUTION: The guide rail 14 of a Z-axis slider 12 which moves in the axial direction of a chuck 4, is equipped to a main spindle box 3. An X-axis slider which moves in the direction for coming in contact to and separating from the axis of the chuck 4 is supported by this Z-axis slider 12, and a tool box is attached to this X-axis slider and thus it becomes possible to place the Z-axis slider 12 nearby the axis of the chuck 4 and to keep a distance between the moving axis of the Z-axis slider 12 and the axis of the chuck 4 constant whereby rigity in cutting is enhanced.