A subtraction processing unit generates a soft portion image representing a soft portion tissue of a subject from first and second radiation images. A body thickness estimation unit estimates a body thickness distribution of the subject on the basis of imaging conditions in a case where the soft portion image and the first and second radiation images are acquired. An approximate body thickness distribution calculation unit calculates an approximate body thickness distribution obtained by approximating the estimated body thickness distribution to a model corresponding to a human body, and a body fat percentage calculation unit calculates a distribution of a body fat percentage in the subject on the basis of the approximate body thickness distribution.
