To provide a method and an apparatus in which whether a metal substance (a nonburning substance) exists so as to be mixed with a substance inside a carton box can be confirmed easily and in which whether a carton box used to seal up a low-radioactivity waste is to be burned or not is judged quickly and surely.

In a method and an apparatus, a plurality of X-ray fluoroscopic images are formed regarding an identical object by projection X-rays in different directions from an X-ray generator 5, a histogram is formed on the basis of the images, it is compared with a threshold value which is stored in advance, and the existence of a metal substance (a nonburning substance) 3 is discriminated. In addition, whether the low-radioactivity waste is to be bruned or not is judged.