The invention is concerned with an imaging capability estimation method and apparatus for an image-formation optical system, which can match the results of direct estimation of an actually visible image to the visibility of that image and is less vulnerable to image processing. According to the method and apparatus, an image of a random pattern 1 is formed through an image-formation optical system S to be inspected. A texture attribute is calculated from the picked-up random pattern image, and the obtained texture attribute is used to make an estimation of the imaging capability of the image-formation optical system S.