An aqueous Astragalus seed extract solution prepared by a method including soaking dried seeds of Astragalus seed in an aqueous solvent to form a suspension, boiling the suspension for at least 30 minutes, and filtering the suspension so as to obtain the Astragalus seed aqueous extract solution, the weight ratio of the dried seeds of Astragalus seed to the extract solution being 1:100 to 75:100.
