Provided are: a method for storing meat stored in a refrigerator or a freezer after being subdivided from a block the method being characterized in that the meat is irradiated with positive ions and negative ions prior to storage in the refrigerator or the freezer a method for delaying the expiration date of a food item that requires refrigerated storage and a method for suppressing multiplication of microbes occurring on the surface of a food item that requires refrigerated storage. Also provided are a method capable of suppressing multiplication of microbes adhered to a food item (in particular meat) that requires refrigerated storage using an ion irradiation device suitable for use in the above methods a method for thereby delaying the expiration date of a food item that requires refrigerated storage and a device suitable for use in the above methods.
