PURPOSE: To make it possible to preserve effectively the freshness, by keeping a fresh edible meat, shellfish, thawed materials and processed products thereof at a low temperature, and keeping the resultant foods in a negatively charged state.

CONSTITUTION: A fresh edible meat, shellfish and thawed materials and processed products thereof are kept at a low temperature to keep the above-mentioned foods in a negatively charged state. For example, a material 1 to be stored is placed on a metallic plate 4 provided on an insulator 5, and the material 1 to be stored and the metallic plate 4 are connected to the respective separate electrodes 2, which are connected to a power source through conducting wires 3 having insulating coverings 6 to charge negatively the material 1 to be stored. In this state, the material 1 to be stored and the metallic plate 4 are isolated with a thin layer of a dielectric, e.g. air or water, and entirely the same as a condenser. Thus, the aimed material 1 to be stored can be negatively charged.