A color adjuster includes: a color specifier that specifies a color when an image former forms an image; a pre-modified candidate acquirer that obtains a calculated value to which a profile for forming an image is applied or a colorimetric value of an image forming result with respect to the color specified by the color specifier; a modification history database that stores the calculated value or the colorimetric value obtained by the pre-modified candidate acquirer, the calculated value and the colorimetric value being associated with a past modified value; a modified value determinator that determines a modified value of the calculated value or the colorimetric value obtained by the pre-modified candidate acquirer on the basis of the past modified value stored in the modification history database; and a modified value outputter that displays or outputs the modified value determined by the modified value determinator.