An air conditioning system includes a plurality of indoor units installed in the same indoor space, an outdoor unit and a control device. The indoor units include respective usage-side heat exchangers capable of setting set temperatures individually. The outdoor unit includes a heat-source-side heat exchanger conducting heat exchange with refrigerant circulating through the usage-side heat exchangers. The control device calculates a representative temperature related value shared by the indoor units using the set temperatures of the indoor units, and switches the indoor units between thermo-ON and thermo-OFF based on the representative temperature related value. The control device calculates the representative temperature related value based on a plurality of temperature differences between the set temperatures and control temperatures in the indoor units.