The present invention provides a technique capable of objectively discriminating the constituent of a subject also in an image in which density difference is not easily discriminated on a gray image obtained by image capturing for medical use using X-rays. An image capturing system for medical use includes: a detecting unit for detecting an X-ray dose by absorbing X-rays passed through a subject in image capturing for medical use and outputting absorbed X-ray dose information; an obtaining unit for obtaining image information of the subject from the absorbed X-ray dose information; an image processing unit for calculating average detection energy in each first predetermined region in the image information; and an output unit for outputting the average detection energy.