To provide a humidity control method capable of reducing a fluctuation frequency of an output level in a dehumidifying operation for a refrigerator, capable of reducing fluctuation (deviation width) in humidity control to maintain stably target set humidity, and capable of saving energy.

Reference set values H1, H2, H3, and a plurality of humidity control levels using upper limit values B, D and lower limit values A, C with the respective reference set values therebetween as control ranges are set stepwisely in a control part of an air conditioner 1, the control levels are made to correspond to dehumidifying levels V1, V2, V3, a control level of humidity is transited to other level combination by a humidity signal from a humidity detector 9, when the control level of the humidity exceeds an allowance range, in the specified level combination out of the combinations of the control levels of the humidity and the dehumidifying levels V1, V2, V3 of the refrigerator 3, and a set value of the humidity set in the each control level of the humidity is automatically changed to control the humidity.