Prior to the image reading processing, a focusing point for each optical magnification that can be set for fine scan is stored. At the time of image reading processing, all images of a photographic film are prescanned after setting reading conditions for prescan, and image verification processing is executed after various setup processes. Thereafter, autofocusing processing is executed with a chart in a film carrier as an object, and then the photographic film begins to be conveyed in the reverse direction for fine scan processing. In cases where the optical magnification of an image next to be read is different from the present optical magnification at the time of fine scanning, the position of each portion is set based on the focusing points stored in advance.