PURPOSE: To efficiently inspect a component having a geometrically complicated shape by generating the two-dimensional image of the component from the signal by an induced eddy current, previously processing the image, and reducing the signal of the geometrical characteristics.

CONSTITUTION: An eddy current probe 18 is scanned at a dovetail groove slot 14, the signal from an eddy current unit 22 is A-D converted by an A-D converter 26 into a digital signal, which is processed by a CPU 30 to generate a two-dimensional image of the slot 14. The many pixels of the image generate a difference at the pixel corresponding to the place having a defect to the gray scale strength corresponding to the eddy current signal at the place of the slot 14 surface represented by the specific pixel. In this case, the image is previously processed, the common geometrical characteristics to the slot 14 and the signal generated by the common background noise are substantially reduced. The region where has doubt of defect is identified from the previously processed image, and the defect signal for the region is determined When the signal exceeds a predetermined reference value, its component is excluded.