An air conditioning system having a plurality of indoor units disposed in the same indoor space, wherein the efficiency of the entire air conditioning system is improved. A plurality of indoor units are installed in the same indoor space, the indoor units include respective indoor heat exchangers (42, 52, 62), and the indoor units are capable of setting set temperatures individually. An outdoor unit (20) includes an outdoor heat exchanger (23) for conducting heat exchange with refrigerant circulating in the indoor heat exchangers (42, 52, 62). Indoor-side control devices (47, 57, 67) perform temperature control of the same indoor space for each indoor unit, using a thermo-ON condition set in advance in accordance with the set temperatures, and relax the thermo-ON condition of thermo-OFF indoor units when the indoor units include both those that are thermo-ON and those that are thermo-OFF and a predetermined condition is satisfied.