1. A color evaluating method of an image display device, which evaluates colors displayed by the image display device, comprising: displaying an image evaluation image, in which a plurality of color regions corresponding to a pixel or a plurality of pixels of the image display device and each having one of a plurality of colors is included and, among the plurality of color regions, at least one color region and at least one other color region having a color similar to that of the one color region are arranged to be adjacent to each other, on the image display device; evaluating the colors displayed by the image display device based on picked-up image data obtained by picking up the color evaluation image displayed by the image display device, wherein the color evaluation image has a color arrangement in which the plurality of color regions are arranged in a belt shape, long sides of the belt-shaped color regions are arranged to be adjacent to one another and, among the plurality of color regions, in at least a given color region except a color region located at an end of the color evaluation image, two color regions adjacent to the given color region have colors similar to that of the given color region; generating color adjustment parameter correcting data based on the evaluation; and correcting color adjustment parameters based on the generated color adjustment parameter correcting data.