An air-conditioning centralized management apparatus (10) for controlling air conditioners including an outdoor unit and an indoor unit includes a main unit (100) that has basic functions for controlling the air conditioners. The main unit (100) includes extension I/Fs (160) that each are connectable to an extension unit (200) that has an extension function for controlling the air conditioners. The extension I/Fs (160) are arranged on, for example, at four locations of the air-conditioning centralized management apparatus (10), on a top side, lower side, left side, and right side thereof, to improve flexibility in connection of the extension unit (200).