An air conditioning apparatus , comprising: a heat source unit having a compression mechanism , a heat-source-side heat exchanger functioning at least as an evaporator, and a heat-source-side expansion value ; a plurality of usage units having usage-side heat exchangers functioning at least as condensers, and usage-side expansion valves ; and a controller configured to regulate the opening degree of the heat-source-side expansion valve on the basis of the opening degrees of the usage-side expansion valves ; wherein the heat source unit further has an accumulator on the intake side of the compression mechanism; the controller is configured to regulate the opening degree of the usage-side expansion valves during an air-warming operation so that the degree of subcooling in the outlets of the usage-side heat exchangers reaches a degree of subcooling target value; characterized in that the controller is configured to set the degree of subcooling target value for each of the usage units in accordance with the required load of each of the usage unit ; the controller is configured to regulate the opening degree of the heat-source-side expansion valve on the basis of a maximum opening degree or an average opening degree among the opening degrees of the usage-side expansion valves of the usage-units ; the controller is configured to regulate the opening degree of the heat-source-side expansion valve so that the amount of depressurization by the usage side expansion valves at the maximum opening degree or an average opening degree among the opening degrees of the indoor expansion valves is sufficient liquid phase to be maintained after depressurization. a heat source unit having a compression mechanism , a heat-source-side heat exchanger functioning at least as an evaporator, and a heat-source-side expansion value ; a plurality of usage units having usage-side heat exchangers functioning at least as condensers, and usage-side expansion valves ; and a controller configured to regulate the opening degree of the heat-source-side expansion valve on the basis of the opening degrees of the usage-side expansion valves ; wherein the heat source unit further has an accumulator on the intake side of the compression mechanism; the controller is configured to regulate the opening degree of the usage-side expansion valves during an air-warming operation so that the degree of subcooling in the outlets of the usage-side heat exchangers reaches a degree of subcooling target value; characterized in that the controller is configured to set the degree of subcooling target value for each of the usage units in accordance with the required load of each of the usage unit ; the controller is configured to regulate the opening degree of the heat-source-side expansion valve on the basis of a maximum opening degree or an average opening degree among the opening degrees of the usage-side expansion valves of the usage-units ; the controller is configured to regulate the opening degree of the heat-source-side expansion valve so that the amount of depressurization by the usage side expansion valves at the maximum opening degree or an average opening degree among the opening degrees of the indoor expansion valves is sufficient liquid phase to be maintained after depressurization. <EOS>