An apparatus includes at least one processor configured to function as following units including a first difference extraction unit configured to extract a first difference between a plurality of images, an alignment unit configured to correct a position of an image with reference to a predetermined subject within the plurality of images, a second difference extraction unit configured to extract a second difference between the plurality of images after the position of the image is corrected by the alignment unit, and a detection unit configured to detect a moving object area based on the extracted first difference and the extracted second difference.