1. An image sensing apparatus comprising an image sensing region where a plurality of pixels are two-dimensionally arrayed, each pixel including a photoelectric conversion unit, an element isolation region having an insulation film to isolate the photoelectric conversion unit from an adjacent pixel, and a semiconductor region arranged below the element isolation region to isolate the photoelectric conversion unit from the adjacent pixel, the semiconductor region including a plurality of diffusion layers at different depth positions, wherein an offset amount of at least one diffusion layer in the semiconductor region with respect to a normal line passing through a center of a light receiving surface of the photoelectric conversion unit in the pixel is larger in a pixel arranged at a peripheral portion of the image sensing region than a pixel arranged at a center of the image sensing region.