To provide a device which set a reference point of a tool with a high precision even without controlling an atmosphere temperature strictly, and a method for this setting.

The reference point of the tool 6 is measured with the tool 6 set on or near the axis line of a main shaft 8, by displacing a measuring section 20 to a measuring position. This minimizes the effect of thermal expansion, whereby highly precise measurement is made regardless of the atmosphere temperature. Quick measurement is also made because it is unnecessary to move the tool 6 to a great extent for measurement. Further, the measuring section 20 is displaced to a retracting position during processing so that the measuring section 20 can not hinder the processing, and processing oil and cutting chips can be restrained from adhering to the measuring section 20.