PURPOSE: To quickly and easily detect deviation of a hole formed in a substrate to be checked from desired values of the center of coordinates and the diameter of said hole by extracting a predetermined number of values from the desired values of the position of said hole.

CONSTITUTION: A board substrate 6 which is an object to be checked is placed on a table 1. A pick-up device 2 is placed confronting to the table 1 in a movable manner longitudinally or laterally relative to the table 1, so that the object 6 to be checked on the table 1 is scanned in the two-dimensional space by the device 2. An output from the device 2 is fed to a control unit 3. Then, in accordance with an instruction from the control unit 3, the pick-up device 2 is moved by a driving device 103 to change its relative position to the table 1. The control unit 3 calculates the difference between stored values and extracted required values corresponding to the stored values, and outputs the result of statistics of the difference to a display unit 5. Accordingly, the deviation of the bore formed in the substrate from desired values of the center of coordinates and the diameter thereof can be quickly and easily detected.