PURPOSE: To judge correction or error of polarity in package of a polar part in a short time and accurately by a method wherein a photosensitive paint is applied previously on the reference side of a polar part and the photosensitive paint is irradiated with light through a mask having a window at a corresponding position thereof to emit light.

CONSTITUTION: A photosensitive paint 11a is applied on the reference side of a polar part 1 while a mask having a window is loaded onto a printed circuit board P corresponding to a painting position of the photosensitive paint 11b on the reference side of the polar part 1 to judge correction or error in polarity of the polar part 1 by condition of emission when a window part is irradiated with light. When the part is packaged in correct polarity, the photosensitive paint 11a applied on the polar part 1 emits light and when it is not, the photosensitive paint 11a emits no light. The photosensitive paint 11b is applied previously in the perimeter of the window facilitates the checking of an inspecting position.