PURPOSE: To sterilize a dry spice in a state thereof retaining the unique aroma and prevent the aroma from being lost by carrying out the coating treatment of the dry spice with a chitosan film and performing the sterilizing treatment with steam.

CONSTITUTION: A dry spice is coated with a chitosan film by spraying, etc., of a chitosan solution and the steam sterilizing treatment of the resultant coated dry spice is then carried out with pressurized steam or superheated steam, etc. The dry spice after the treatment, together with the coating film of the chitosan, is pulverized and used for a food without any problem. The chitosan solution is preferably a weak acid solution of acetic acid, lactic acid, ascorbic acid, etc., and the concentration is preferably 1-2wt.%.