1. A radiographic image analysis device that analyzes a subject image of a subject obtained by radiography to estimate a body thickness distribution of the subject, the device comprising: an image acquisition unit that acquires the subject image; a virtual model acquisition unit that acquires a virtual model of the subject having a predetermined body thickness distribution; an estimated image generation unit that generates a composite image of an estimated primary X-ray image, which is obtained by estimating a primary X-ray image of the virtual model obtained by radiography from the virtual model, and an estimated scattered X-ray image, which is obtained by estimating a scattered X-ray image of the virtual model obtained by radiography from the virtual model, as an estimated image which is obtained by estimating a radiographic image of the subject obtained by radiography; a correction unit that corrects the body thickness distribution of the virtual model such that a difference between the estimated image and the subject image is reduced; and a body thickness distribution determination unit that determines the corrected body thickness distribution of the virtual model as the body thickness distribution of the subject.