To provide a freshness keeping device capable of storing foods such as vegetables and fruits or plants such as flowers and garden plants for a long time while keeping freshness thereof.

A freshness keeping device includes a sheet box 3 for housing stored articles, a mist generator 1 for supplying nano mist and negative ions while circulating them in the sheet box 3, and a prefabricated chamber 6 for covering the sheet box 3. In the prefabricated chamber 6, a cooler 7 for cooling the sheet box 3 from the outside is provided.