PURPOSE: To conduct tool control by correcting tool data in a work program of an M/C side, and transmitting, on the M/C side, information on a working tool and breakage and the like of a tool every time to a personal computer (PC) side by means of a control code to renew tool information stored in the PC.

CONSTITUTION: Information on tools is beforehand stored in a personal computer (PC) and an ID element 7 of a tool 5. Information transmission between the PC 1 and an M/C 8 is performed by means of a control code 9 which is ordinarily used in general. When a desired tool 5 is fitted into a main spindle 10 based on a work program, reading of the ID element 7 in the tool 5 is conducted so that information related to that tool 5 stored in the PC 1 is called every time when the PC 1 is operated. Accordingly, information related to the tool 5 in the M/C 8 is renewed and predetermined work based on this renewed tool content is conducted.