The invention concerns a method of producing aged garlic in which its antioxidation capability is significantly increased as compared to that of raw garlic which is used as a raw material for producing the aged garlic without reducing the essential effectiveness of garlic, S-arylcysteine that does not exist in raw garlic is generated, and the content of polyphenol is increased. The method of producing aged garlic according to the invention is characterized by comprising the steps of aging raw garlic with hot air at 40 to 90.degree. C. for about 300 hours, naturally drying the resultant garlic for approximately 40 hours and then ageing the garlic with hot air at 20 to 30.degree. C. for 30 to 50 hours again. In the step of aging the garlic with hot air at 40 to 90.degree. C. for 280 to 320 hours, a plurality of pieces of the raw garlic is placed in a steel bin and then the steel bins are put into a container for aging.