A refrigerating cycle apparatus operation control method for a refrigerating cycle apparatus comprising: - a refrigerant circuit that is configured by connecting a compressor, a high-pressure heat exchanger (2, 6, 6P, 6Q, 6R), a throttling means (4, 4P, 4Q, 4R), and a low-pressure heat exchanger (6, 6P, 6Q, 6R, 2) using liquid piping (5, 31) and gas piping (8, 32), and through which a refrigerant is cycled; - heated medium conveying means (3, 7, 7P, 7Q, 7R) and cooled medium conveying means (7, 7P, 7Q, 7R) that convey a heated medium and a cooled medium relative to the high-pressure heat exchanger (2, 6, 6P, 6Q, 6R) and the low-pressure heat exchanger (6, 6P, 6Q, 6R, 2); - detecting means (11-15, 15P, 15Q, 15R, 16, 16P, 16Q, 18R, 17, 17P, 17Q, 17R, 18) that detect temperature and pressure of the refrigerant in the refrigerant circuit and temperatures of the heated medium and the cooled medium; and - controlling means that sets a high-pressure pressure target value from thermal load and temperature conditions that are based on refrigerant information that has been obtained from the detecting means (11-15, 15P, 15Q, 15R, 16, 16P, 16Q, 18R, 17, 17P, 17Q, 17R, 18), and controls at least one of a rotational frequency of the compressor, a degree of opening of the throttling means (4, 4P, 4Q, 4R), a flow rate of the heated medium, or a flow rate of the cooled medium so as to match a high-pressure pressure to the high-pressure pressure target value that has been set, characterized in that the controlling means sets a threshold value when the high-pressure pressure target value is set, and modifies a method for setting the high-pressure pressure target value depending on whether the high-pressure pressure is greater than or equal to the threshold value or less than the threshold value when the high-pressure pressure target value is decided, wherein the high-pressure pressure target value is calculated based on the thermal load and an inflow temperature of the heated medium if the high-pressure pressure is less than the threshold value when the high-pressure pressure target value is set; and wherein the high-pressure pressure target value is calculated based on the thermal load, an inflow temperature of the heated medium, and an inflow temperature of the cooled medium if the high-pressure pressure is greater than or equal to the threshold value when the high-pressure pressure target value is set. - a refrigerant circuit that is configured by connecting a compressor, a high-pressure heat exchanger (2, 6, 6P, 6Q, 6R), a throttling means (4, 4P, 4Q, 4R), and a low-pressure heat exchanger (6, 6P, 6Q, 6R, 2) using liquid piping (5, 31) and gas piping (8, 32), and through which a refrigerant is cycled; - heated medium conveying means (3, 7, 7P, 7Q, 7R) and cooled medium conveying means (7, 7P, 7Q, 7R) that convey a heated medium and a cooled medium relative to the high-pressure heat exchanger (2, 6, 6P, 6Q, 6R) and the low-pressure heat exchanger (6, 6P, 6Q, 6R, 2); - detecting means (11-15, 15P, 15Q, 15R, 16, 16P, 16Q, 18R, 17, 17P, 17Q, 17R, 18) that detect temperature and pressure of the refrigerant in the refrigerant circuit and temperatures of the heated medium and the cooled medium; and - controlling means that sets a high-pressure pressure target value from thermal load and temperature conditions that are based on refrigerant information that has been obtained from the detecting means (11-15, 15P, 15Q, 15R, 16, 16P, 16Q, 18R, 17, 17P, 17Q, 17R, 18), and controls at least one of a rotational frequency of the compressor, a degree of opening of the throttling means (4, 4P, 4Q, 4R), a flow rate of the heated medium, or a flow rate of the cooled medium so as to match a high-pressure pressure to the high-pressure pressure target value that has been set, characterized in that the controlling means sets a threshold value when the high-pressure pressure target value is set, and modifies a method for setting the high-pressure pressure target value depending on whether the high-pressure pressure is greater than or equal to the threshold value or less than the threshold value when the high-pressure pressure target value is decided, wherein the high-pressure pressure target value is calculated based on the thermal load and an inflow temperature of the heated medium if the high-pressure pressure is less than the threshold value when the high-pressure pressure target value is set; and wherein the high-pressure pressure target value is calculated based on the thermal load, an inflow temperature of the heated medium, and an inflow temperature of the cooled medium if the high-pressure pressure is greater than or equal to the threshold value when the high-pressure pressure target value is set.