To provide a freezer preventing unnecessary warming of the interior and preventing interior dew formation and dew formation of a freezing target while maintaining the interior at low temperature all the time.

The freezer includes: compressed dry air supply units 14, 15 supplying dry air to inside of a freezer body 1 and inside of an auxiliary chamber 2; and flow control valves 12a, 12b controlling the supply amount of the dry air. The freezer further includes: a first temperature sensor 18 detecting interior dew-point temperature; a second temperature sensor 19 detecting temperature of an interior freezing target 23; a first pressure sensor 20 detecting interior air pressure; a second pressure sensor 21 detecting indoor air pressure; and a third pressure sensor 22 detecting outside air pressure. A control unit 10 controls the supply amount of dry air from the compressed dry air supply units 14, 15 to the interior and the indoor side so that interior and indoor air pressure becomes larger than the outside air pressure all the time, and at the same time, keeps the dew-point temperature lower than the temperature of the freezing target all the time.