This invention provides a large image pickup apparatus for, e.g., X-rays that can provide a seamless image by using a plurality of single-crystal silicon image pickup elements. More specifically, the image pickup apparatus includes an image pickup region where a plurality of pixels which include photoelectric conversion units are arranged to pick up an object image by dividing the object image into a plurality of regions, and a scan circuit (501, 507) arranged between the plurality of photoelectric conversion units in the region to commonly process the plurality of pixels and/or signals from the plurality of pixels.