A refrigeration cycle system is capable of reducing an amount of information required to be specified in advance, reducing a computational processing load, reflecting differences in actual installation conditions, and speeding up stabilization of an operational state in which the total amount of required input energy is reduced. A refrigeration cycle system is provided with a plurality of actuators, including outdoor fan motors, compressors, indoor fan motors, and the like for causing a refrigerant circuit to carry out a refrigeration cycle. A control unit obtains the slope at the current evaporation temperature and/or the current condensing temperature on a graph of the function between the actuators and the evaporation temperature or the condensing temperature, and updates the value of the target evaporation temperature and/or the target condensing temperature so that the sum of the input energy to the actuators is less that the current level.