The present invention provides a process for highly purifying C.I. Solvent Black 3 using specific aromatic hydrocarbons or petroleum hydrocarbons. The process comprises dissolving C.I. Solvent Black 3 represented by ##STR1## in an organic solvent selected from the group consisting of aromatic hydrocarbons having 6 to 12 carbon atoms and petroleum hydrocarbons having 6 to 10 carbon atoms followed by filtering, and then removing the solvent.