PURPOSE: To prevent such error detection as detects dust, a stain, or the like, which adheres to the surface of a matter to be examined, as a defective part such as a pinhole.

CONSTITUTION: Permeating illuminating light 3 is radiated from the lower side of an inner lead 1 to be examined and auxiliary illuminating light 10 is radiated from the side face of the inner lead 1 to the surface of the inner lead 1 at the same time. Reflected light 17, which is reflected by a stain and the like on the surface of the inner lead 1 irradiated by the auxiliary illuminating light 10, is received by an image pickup camera 12, and the image is picked up.