PURPOSE: To prevent an accident before occurrence safely supervising a machining part by mounting a camera being able to adjust its position to a spindle head or to a part following a movement of the spindle head and enabling an NC image and a machining image to be divisionally displayed in a CRT image plane.

CONSTITUTION: A waterproof cover 13 with a built-in industrial small camera is mounted being able to adjust a position of camera angle to the point end of a spindle head 3 through a mounting metal fixture, being constituted so as to display an image in an image plane of a CRT8 in an NC unit, and an NC image and a machining image can be divisionally displayed. As the result, a machining part can be safely supervised by enabling the vision of difficulty due to overlapping both the images to be avoided. Accordingly, early discovering unexpected abnormality during cutting with a less hazard by an error control of tool length correction, original point correction, etc., an accident can be prevented before occurrence.