PURPOSE: To minimize error and perform highly accurate drilling by calibrating an error factor between servo traveling data and image data after forming multiple holes in a substrate located in the image window of an image pick-up camera and obtaining a hole center.

CONSTITUTION: A camera type reference drilling machine 100 picks up an image of the reference mark of a substrate 11 placed on the upper part of a guide hole in a machining table 10 with an image pick-up camera 46 which is disposed on it, processes the pick-up image, and detects the central position of the reference mark. It drives multiple servo-motors 38, 32, 22 in order so as to move a drilling means 50 to the central position of the reference mark. Multiple holes are formed in the substrate 11 located in an image window of the image pick-up camera. Next, the images of the holes are processed to obtain a hole center. Then, an error function is obtained based on servo traveling data and image data. Error factors between respective data are calibrated by means of least square method.