A color gamut data creating device includes a locating unit, and an extracting unit. The locating unit locates characteristic points based on the measurement points on a target plane. The extracting unit extracts at least three vertices of a color gamut from among the characteristic points. The at least three vertices satisfy the 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.