PURPOSE: To rapidly conduct an inspection by a method wherein the average of reflectances continuously measured in a reference value measuring area of a non-printing part is set as a reference value, reflectances in a space part and a bar part in a printing area are continuously measured, and deviation amounts of maximum and minimum reflectance values in the space part are compared with a judging level for judging a stain.

CONSTITUTION: A reference value measuring area A of a printed body 1 is scanned by a measuring part 2 with a photosensor consisting of a light-emitting element and a light-receiving element. The light are continuously received by the photosensor and arithmetically processed by an operation part to be converted to reflectances. Futhermore, the average of the reflectances is calculated to be set as a reference value. Next, a bar code printing area B is scanned Similarly, reflectances in a space part and a bar part are continuously measured. Maximum and minimum reflectances in the space part are found. A judging part arithmetically processes deviation values of the maximum and minimum values from the reference value, compares the deviation values with a judging level, judges a white stain and a stain, and displays the result on a display part.