A pigment composition can be prepared by wet or dry milling a pigment selected from the group consisting of dianthraquinone pigments, diketopyrrolopyrrole pigments and a mixture thereof, in the presence of a compound represented by Formula 1: ##STR00001## where Q denotes --NH(CH.sub.2).sub.nNR.sup.1(R.sup.2) group or hydroxyl group, and R denotes --NH(CH.sub.2).sub.nNR.sup.1(R.sup.2) group.