1. A color gamut data creating device comprising: a receiving unit that receives measurement points concerning a device, the measurement points being defined in a color space that is capable of representing hue by a hue angle, the hue angle being defined by an axis perpendicular to an achromatic axis that represents lightness; a locating unit that locates characteristic points based on the measurement points on a target plane that has a constant angle of the hue angle; an extracting unit that extracts at least three vertices of a color gamut from among the characteristic points, the at least three vertices satisfying conditions that a first point, which is any one of the at least three vertices, is located within a reference distance from a second point adjacent to the first point from among the at least three vertices, and that all cross products that are calculated by a vector from the first point to the second point and vectors from the first point to any characteristic points that are located within the reference distance from the first point have the same sign; and a data creating unit that creates color gamut data indicative of the color gamut, the color gamut indicating a distribution range of the characteristic points based on the at least three vertices extracted by the extracting unit.