Provided is a method of purifying hydrochloric acid by removing an organic substance having a boiling point of - 25 °C to 120 °C under atmospheric pressure from an organic substance-containing hydrochloric acid that contains the organic substance and has a hydrogen chloride concentration higher than an azeotropic hydrogen chloride concentration under atmospheric pressure. The method includes the step of subjecting the organic substance-containing hydrochloric acid to distillation using a distillation tower at an operation pressure set such that an azeotropic hydrogen chloride concentration under the operation pressure is higher than the hydrogen chloride concentration of the organic substance-containing hydrochloric acid, to distill out the organic substance from the top of the distillation tower.