PURPOSE: To accomplish the titled reduction without any change in free carbon content in the coal tar and without imparing characteristics as binder, by bringing feedstock coal tar into contact with hydrochloric acid (aqueous solution) in the production of coal tar pitch.

CONSTITUTION: First, hydrochloric acid in the form of an aqueous solution (pref. with a concentration 0.02W1%) is added to coal tar to bring the both into through contact with each other by agitation, etc. Next, the resultant system is left at rest, e.g., in a tank to separate a coal tar layer from hydrochloric acid layer; the upper layer, i.e., hydrochloric acid one being drawn out, while the coal tar layer being incorporated with water for scrubbing followed by agitation, then being left at rest followed by drawing the upper aqueous layer out, thus obtaining the objective coal tar of higher purity.