PROBLEM TO BE SOLVED: To provide an oxygen-reduced unit operating so as to obtain a predetermined oxygen concentration, an oxygen-reduced system and a refrigerator having the oxygen-reduced unit.SOLUTION: The oxygen-reduced unit in the embodiment includes: an oxygen-reduced element having an anode, a cathode, and an electrolyte membrane held by the anode and cathode a voltage applying unit for applying a voltage to the oxygen-reduced element a current measuring unit for measuring the current of the oxygen-reduced element and a control part for controlling a voltage to be applied to the oxygen-reduced element by the voltage applying unit based on the current change rate calculated from a first current value obtained by the current measuring unit, a second current value obtained from the current measuring unit after the lapse of a predetermined time, and the predetermined time.
