1. An MTF measuring system for calculating an MTF to be an index for evaluating a lens performance by MTF calculating means to acquire MTF data based on object image data obtained by photographing an object through a lens, and generating MTF curve image data indicative of an MTF curve based on the MTF data thus acquired, comprising: measuring result screen generating means for generating measuring result screen data indicative of an object image and an MTF curve image based on the object image data and the MTF curve image data; and display control means for displaying a measuring result screen on a display portion based on the measuring result screen data generated by the measuring result screen generating means; wherein a plurality of markers taking a predetermined shape is printed on the object, the MTF calculating means calculates an MTF of each of the markers taking the predetermined shape in the object image data acquired by photographing the markers, thereby acquiring the MTF data in each marker position, and the measuring result screen generating means generates measuring result screen data having an MTF curve image in the marker position disposed in the vicinity of the marker position based on the MTF curve image data generated from the MTF data; and further comprising: luminance calculating means for calculating a luminance level of a white region in the vicinity of each marker position in the object image data, thereby acquiring luminance level data indicative of the luminance level in the marker position; and luminance image generating means for generating luminance level image data indicative of a luminance level image of the white region in the vicinity of each marker position based on the luminance level data thus acquired, the measuring result screen generating means generating measuring result screen data indicative of each MTF curve image and each luminance level image which correspond to each marker position on the object image together with the object image based on the object image data, the MTF curve image data and the luminance level image data.