For the purpose of simply sterilizing drinking water and food products utilizing carbon dioxide that is in a gaseous state, there is provided a method for treating a food product, which is characterized in that the method comprises allowing microscopic bubbles of carbon dioxide to come into contact with a food product containing microorganisms or enzymes at a pressure of 0.2 to 2 MPa, thereby sterilizing the microorganisms or deactivating the enzymes contained in the food product.