An air conditioner is provided that may include a plurality of units including an outdoor unit and an indoor unit, the plurality of units being distributed at a plurality of layers or levels or stories in a building; and a controller configured to monitor and control the plurality of units. The controller and the plurality of units may include a communication unit configured to transmit/receive data in a wireless communication unit, respectively, and the communication unit may transmit/receive the data using a sub-giga band frequency. The plurality of units may transmit/receive data in a wireless communication scheme so that an indoor unit and an indoor unit, and an indoor unit and an outdoor unit may directly communicate with each other in a wireless scheme, and the indoor unit may directly communicate with the controller.