An image processing apparatus configured to obtain a resized image of a suitable size in a case where a plurality of image data are enlarged or reduced, while keeping a vertically long or horizontally long state of the image. Thus, a matched state between a resize object image and a resize rectangle as target values for a resized image as to whether being vertically long or horizontally long is determined. Responsive to a result of determination, the resize rectangle is rotated 90 degrees, and the resize object image is enlarged or reduced such that the enlarged or reduced resize object image is matched with the resize rectangle rotated.