An image processing apparatus corrects input image data on the basis of the image data and foreign substance information including information associated with a position and a size of a foreign substance adhering near an image sensor in an image capturing apparatus which has captured the image data. The apparatus includes a correction unit which corrects the image data on the basis of the image data and the foreign substance information so as to reduce an influence of a shadow of the foreign substance cast in the image data, a uniformity determination unit which determines the uniformity of an image in a region surrounding the foreign substance in the image data, and a control unit which, when the uniformity determination unit determines that the uniformity is lower than a predetermined value, prevents the correction unit from correcting the image data.