PURPOSE: To prevent the spoilage of mandarin oranges in a cabinet, e.g. a refrigerator, and preserve the mandarin oranges without losing the freshness, by supplying ozone gas into air in the cabinet.

CONSTITUTION: Mandarin oranges in bags with opened mouths are contained in a refrigerator 10 cooled and adjusted to about 5°C with electronic controlling equipment 12, and ozone gas in an adequate amount is fed into air in the refrigerator 10 with ozonizing equipment 16, etc. The growth of blue molds on the epidermises of the mandarin oranges is prevented, and the spoilage of the mandarin oranges during the preservation is prevented. Oxygen generated by decomposition of the ozone gas is fed to the mandarin oranges in the bags to assist the absorbing action thereof, and the freshness of the mandarin oranges is kept.