To improve a processing speed by using an inexpensive, general image- processing device while surely distinguishing a flaw of a container itself from a foreign matter on the surface of the container in a foreign matter inspection method for detecting a minute, foreign matter in a solution.

An illuminated container is captured as a plurality of images (image pick-up step). In each inspection unit while dividing the images into two inspection units, an inspection image for comparison is generated from brightness information in the pixel same as each pixel in the above image (steps for generating an inspection image for comparison) (S4-S7). Further, by obtaining the difference between the above two generated inspection images for comparison, the presence or absence of a foreign matter can be judged (steps for judging the presence or absence of foreign objects) (S8-S11).