An image processing apparatus includes: an acquisition unit that acquires a radiographic image of a breast and information indicating a thickness of the breast in capture of the radiographic image； and a derivation unit that derives a percentage of mammary glands of a breast image in the radiographic image acquired by the acquisition unit using different methods in a case in which the thickness of the breast is equal to or greater than a predetermined thickness and a case in which the thickness of the breast is less than the predetermined thickness.
