Accurate alignment of images is provided when a plurality of images are obtained with a plurality of radiation source positions, such as in tomosynthesis imaging. An image obtaining unit (20) obtains a plurality of images by imaging a subject (2) and at least one marker with a plurality of radiation source positions. A radiation source position calculating unit (36) calculates positional information of each radiation source position relative to a reference radiation source position based on positional information of at least one marker image contained in each of the images. A reconstruction unit (22) reconstructs the images with aligning the images based on the position of each radiation source relative to the reference radiation source position to generate a tomographic image.
