A control-information detecting apparatus for a refrigeration air-conditioner using a non-azeotrope refrigerant is equipped with a temperature detector and a pressure detector at the refrigerating cycle of the air-conditioner, which cycle is formed by connecting a compressor, a condenser, a decompressing device, and an evaporator, to detect the temperature and the pressure of the refrigerant circulating the cycle for obtaining the circulation composition of the refrigerant with the composition computing unit thereof. The usual optimum operation of the cycle is thereby enabled even if the circulation composition of the refrigerant has changed.