An image sensing system comprises an image sensor having an image sensing surface, a filter arranged between the image sensing surface and an optical system which forms an image of an object on the image sensing surface, a sensor configured to detect a luminance of the object in a band in the vicinity of a cutoff wavelength of the filter relative to an average luminance of the object via the optical system, and a corrector configured to execute color shading correction of the image, sensed by the image sensor, using a color shading correction coefficient determined by the relative luminance detected by the sensor.