Intelligent reflecting device

An intelligent reflecting device comprising:

• a first substrate including a first base and a plurality of patch electrodes arranged in a matrix at regular intervals along a first direction and a second direction;
• a second substrate including a second base and a common electrode opposed to the plurality of patch electrodes;
• a liquid crystal layer held between the first substrate and the second substrate;
• a heat exchanger provided in contact with the second substrate;
• a temperature sensor that detects a temperature of the liquid crystal layer;
• and
• a temperature controller that controls the heat exchanger based on the temperature detected by the temperature sensor, wherein
• an incident wave is incident on an incidence surface of the first substrate, and
• the heat exchanger is provided on a surface opposed to the incidence surface.