A control unit sets an angle of incidence of radiation, incident on a detection surface of a radiation detector with respect to the detection surface, to a plurality of angles different from each other including an angle (0 degrees) in a normal direction of the detection surface, and acquires at least one of a plurality of projection images captured by the radiation detector in accordance with the angle of incidence or reconstructed images reconstructed using the projection images. In addition, the control unit generates a first synthetic mammogram image on the basis of the one image. In addition, the control unit 40 generates a second synthetic mammogram image by synthesizing a high-frequency image having a high-frequency component higher than a predetermined frequency of the first synthetic mammogram image and a low-frequency image having a low-frequency component of equal to or lower than a predetermined frequency of a zero-degree projection image.
