Disclosed is a method for measuring luminance of each of entire pixels two-dimensionally arranged in a light-emitting display panel at regular intervals, using an image sensor in which light receiving elements are two-dimensionally arranged at regular intervals, the method including: providing an optical lens between the light-emitting display panel and the image sensor, and adjusting distances between the light-emitting display panel, the image sensor, and the optical lens by setting intervals of images of the entire pixels to be N times as large as intervals of the light receiving pixels, where N is a natural number, the images being to be formed on a light receiving surface of the image sensor through the optical lens; displaying, on the light-emitting display panel, a display pattern in which predetermined pixels from among the entire pixels produce a luminescence; and measuring the luminance of the predetermined pixels, using the light receiving elements.