In the present invention, an FBP algorithm is used, and without losing calculation efficiency, noise within an image is effectively reduced. A noise weighting determination unit (114A), in accordance with at least a specific noise model, determines a weighted value for weighting projection data. A filter shaping unit (114B) shapes at least one reconstruction filter on the basis of a parameter that includes a weighted value. An image generation unit (114C) generates an image on the basis of the reconstruction filter.