PROBLEM TO BE SOLVED: To provide an image analysis device, a method and a program, capable of analyzing a subject image which is captured by radiating radiation ray to a subject, for estimating body thickness distribution of the subject.SOLUTION: The image analysis method is configured to: acquire a subject image Ik acquire a virtual model M of the subject comprising a prescribed body thickness distribution create an image obtained by combining an estimated primary ray image in which a primary ray image obtained by radiation ray photographing of the virtual model M is estimated from the virtual model M, and an estimated scattered ray image in which a scattered ray image obtained by radiation ray photographing of the virtual model M is estimated from the virtual model M, as an estimated image Im in which a radiation ray image obtained from radiation ray photographing of the subject is estimated correct the body thickness distribution of the virtual model M so that difference between the estimated image Im and the subject image Ik is reduced then, determine the corrected body thickness distribution of the virtual model M as body thickness distribution of the subject.SELECTED DRAWING: Figure 2