1. An image processing apparatus comprising: a first image processor configured to receive, as a sequence of images, a plurality of images which is captured by sequentially shifting a shooting position in a predetermined direction, and set a first overlapping area overlapping a priority area which is to be used preferentially in the sequence of images, as a use-prohibited area with respect to images in the sequence of images other than the first image, the images including the first overlapping area; a second image processor configured to set a second overlapping area of a second or third image as a use-prohibited area based on whether the second overlapping area is larger than a predetermined boundary margin, the second overlapping area overlapping the second and third images, and the second and third images having sequence orders being separated by a predetermined spacing in the sequence of images; and an image generator configured to generate an output image using areas of the plurality of images included in the sequence of images, excluding areas which are set as the use-prohibited areas by the first age processor and the second image processor.