To provide a room humidity conditioning system using a humidity conditioning material such as a humidity conditioning building material, capable of forming a comfortable humidity environment by getting great performance out of the humidity conditioning material such as the humidity conditioning building material.

This system comprises an air conditioner 2 with humidity control function, a moisture content sensor 6 detecting the moisture content of the humidity conditioning material provided in a room 1 such as a bedroom, and a control part 6 controlling the air conditioner 2 to perform an operation for adjusting the moisture content of the humidity conditioning material to a moisture content necessary for making the humidity conditioning material perform humidity conditioning work so as to keep the indoor humidity at a fixed value for a desired time in spite that the factor of a humidity change is present within the room. The system preferably further comprises a humidity sensor 4 detecting the indoor humidity, so that the control part 6 performs, during the adjusting operation of the moisture content of the humidity conditioning material, the control for adjusting the indoor humidity to the desired humidity based on a signal from the humidity sensor 4.