PURPOSE: To obtain the titled substance free of the bitter taste and characteristic flavor of licorice and useful as a medicine, in high purity, by treating an aqueous solution of licorice extract with a porous adsorbent composed of an aromatic polymer having amino groups and hydroxy groups, at a specific pH, thereby removing the impurities from the extract.

CONSTITUTION: An aqueous solution of licorice extract containing glycyrrhizin and obtained by extracting roughly crushed licorice root with water, is adjusted to pH 4W6, and passed through a column packed with a porous adsorbent composed of an aromatic polymer having amino groups and hydroxy groups to adsorb and remove the impurities. The column effluent is concentrated under reduced pressure, and spray-dried to obtain powdery objective compound. The adsorption is preferably carried out using a porous ampholytic ion exchange resin having phenolic hydroxyl groups under acidic or neutral conditions. The used adsorbent can be regenerated by passing an alkaline aqueous solution through the column.