PURPOSE: To efficiently obtain the subject compound useful as medicines, etc., from an inexpensive raw material according to simple operation by extracting a soy sauce cake, etc., with an organic solvent.

CONSTITUTION: A soy sauce cake or soy sauce oil is extracted with an organic solvent such as ethyl alcohol and the resultant extract is concentrated to dryness, then dissolved in a hydrous alcohol, adsorbed on an adsorbent resin and sufficiently washed with water to elute impurities with a hydrous alcohol of about 20% concentration. The resultant substance is subsequently eluted with a 80% hydrous alcohol to afford the objective compound.