PURPOSE: To save labour of an operator while improving the working ratio of a copying machine by interchanging automatically styli adapted to tools as well as the tools in the copying milling machine or the like.

CONSTITUTION: A stylus magazine 31 is electrically interlocked with a tool magazine 4 to automatically interchange styli 15 as well as tools 3. In the interchange of the styli 15, a stylus head 10 is lifted by the operation of hydraulic cylinders 9 and 43 to slide the magazine 31 for fitting and holding a disk 33 receiving section 34 in a collar 20 of a holder 16 of a stylus device 14. Next, the magazine 31 is moved downward by a hydraulic cylider 42 to withdraw the stylus device 14 from the head 10 and rotate the disk 33 with a reversible motor 39 and a Geneva 37 so that a new stylus device 14 is indexed to be located right below the head and lifted by the hydraulic cylinder 42 to be attached to the head. Thus, the working ratio can be improved.