A control device (4) detects a frosted state or a pre-frosting state of an evaporator in a refrigeration cycle device (2, 102) which includes multiple evaporators (24A, 24B, 24C, 24D). The control device controls a frosting determination temperature (FT), which is a temperature of a predetermined representative evaporator among the multiple evaporators or a temperature related to the temperature of the representative evaporator, to be lower than temperatures of the other evaporators other than the representative evaporator (step S30). The control device determines that the multiple evaporators are in the frosted state or the pre-frosting state when the frosting determination temperature is lower than or equal to a frosting threshold temperature in a state where the temperature of the representative evaporator is controlled to be lowest among the multiple evaporators (step S40, step S41). Accordingly, the number of temperature detectors used for detecting frosting of the multiple evaporators can be reduced.