A space in which negative charges are predominant is formed independently of the structure of equipment or an apparatus in a process of producing or processing a food or food material by actively exploiting the functions of charcoal or bamboo charcoal.A paint 2a composed mainly of graphitized charcoal or bamboo charcoal is applied to a ceramic sheet 21 in such an amount that the ceramic sheet 21 has a resistance value of 3 ± 1 kilohms (KΩ), thereby forming a plane electrode 2 a side of the plane electrode 2 to which the paint 2a is not applied is attached to the wall surface portions 11, the ceiling portion 12, and a chamber 12a of a storeroom 1a or 1b such that the side of the plane electrode 2 is in contact with the wall surface portions 11, the ceiling portion 12, and a chamber 12a of the storeroom 1a or 1b and a negative direct voltage in the range of -70 to -100 volts is applied from an electrification member 3 to a plane electrode 2 (the paint 2a) through an electric wire to excite carbon in the plane electrode 2, thereby forming a space in which negative charges are predominant in the storeroom 1a or 1b using electrons (e) in the plane electrode 2 or emitted.
