A method of controlling an air conditioner, the method comprising: collecting indoor unit data of each of a plurality of indoor units (30a, 30b, 30c) connected to an outdoor unit; matching each of the plurality of indoor units (30a, 30b, 30c) to one of a plurality of clusters included in cluster classification data, based on indoor unit data collected from each of the plurality of indoor units; controlling a total flow rate of refrigerant supplied to the plurality of indoor units (30a, 30b, 30c) based on a total load of the indoor units (30a, 30b, 30c), which is determined based on the indoor unit (30a, 30b, 30c) data of the respective indoor units (30a, 30b, 30c); controlling an individual flow rate of refrigerant flowing to the respective indoor units (30a, 30b, 30c) based on the indoor unit data of the respective indoor units (30a, 30b, 30c); re-collecting indoor unit data of the respective indoor units (30a, 30b, 30c); and based on a change in the total load of the indoor units (30a, 30b, 30c), which is determined based on the re-collected indoor unit data of the respective indoor units (30a, 30b, 30c), re-controlling the total flow rate of the refrigerant supplied to the plurality of indoor units (30a, 30b, 30c)(S260, S270), wherein the plurality of clusters is classified into a plurality of cluster levels (LV1, LV2, LV3, LV4, LV5) that increase based on a load required for the indoor unit (30a, 30b, 30c), wherein the indoor unit data comprise indoor temperature, indoor humidity, and a number of occupants, which are sensed by an indoor sensing unit, and set temperature input by a user, wherein the re-collecting of the indoor unit data is followed by determining a change in a degree of overheat of an indoor space based on a change in a number of persons present in the indoor space where the respective indoor units (30a, 30b, 30c) are installed, and re-controlling the individual flow rate of the refrigerant flowing to the respective indoor units (30a, 30b, 30c) based on the change in the degree of overheat of the indoor space where each of the indoor unit (30a, 30b, 30c) is disposed. collecting indoor unit data of each of a plurality of indoor units (30a, 30b, 30c) connected to an outdoor unit; matching each of the plurality of indoor units (30a, 30b, 30c) to one of a plurality of clusters included in cluster classification data, based on indoor unit data collected from each of the plurality of indoor units; controlling a total flow rate of refrigerant supplied to the plurality of indoor units (30a, 30b, 30c) based on a total load of the indoor units (30a, 30b, 30c), which is determined based on the indoor unit (30a, 30b, 30c) data of the respective indoor units (30a, 30b, 30c); controlling an individual flow rate of refrigerant flowing to the respective indoor units (30a, 30b, 30c) based on the indoor unit data of the respective indoor units (30a, 30b, 30c); re-collecting indoor unit data of the respective indoor units (30a, 30b, 30c); and based on a change in the total load of the indoor units (30a, 30b, 30c), which is determined based on the re-collected indoor unit data of the respective indoor units (30a, 30b, 30c), re-controlling the total flow rate of the refrigerant supplied to the plurality of indoor units (30a, 30b, 30c)(S260, S270), wherein the plurality of clusters is classified into a plurality of cluster levels (LV1, LV2, LV3, LV4, LV5) that increase based on a load required for the indoor unit (30a, 30b, 30c), wherein the indoor unit data comprise indoor temperature, indoor humidity, and a number of occupants, which are sensed by an indoor sensing unit, and set temperature input by a user, wherein the re-collecting of the indoor unit data is followed by determining a change in a degree of overheat of an indoor space based on a change in a number of persons present in the indoor space where the respective indoor units (30a, 30b, 30c) are installed, and re-controlling the individual flow rate of the refrigerant flowing to the respective indoor units (30a, 30b, 30c) based on the change in the degree of overheat of the indoor space where each of the indoor unit (30a, 30b, 30c) is disposed.