A method for detecting whether a different refrigerant has been charged into a refrigeration apparatus including a refrigerant circuit through which a refrigerant circulates and which thus performs a refrigeration cycle, the method comprising: a charging step of charging a refrigerant into the refrigerant circuit; a characteristics determination step of determining whether saturation temperature characteristics of the refrigerant charged in the charging step are identical to saturation temperature characteristics of a previously determined normal refrigerant, the saturation temperature characteristics of the refrigerant being derived from a pressure and a temperature of the refrigerant; an alerting step of, when, in the characteristics determination step, a determination is made that the saturation temperature characteristics of the refrigerant charged in the charging step are different from the saturation temperature characteristics of the previously determined normal refrigerant, issuing an alarm indicating that the charged refrigerant is different from the normal refrigerant; an inputting step of, when, in the characteristics determination step, a determination is made that the saturation temperature characteristics of the refrigerant charged in the charging step are identical to the saturation temperature characteristics of the previously determined normal refrigerant, manually inputting a type of the charged refrigerant to a data storage; a forcible prohibition step of, when the type input to the data storage is identical to a type of a predetermined refrigerant different from the previously determined normal refrigerant, forcibly prohibiting start of operation of the refrigeration apparatus, and in the characteristics determination step, a temperature detected by an outside temperature sensor that measures an outside temperature is used in derivation of the saturation temperature characteristics of the refrigerant as the temperature of the refrigerant. a charging step of charging a refrigerant into the refrigerant circuit; a characteristics determination step of determining whether saturation temperature characteristics of the refrigerant charged in the charging step are identical to saturation temperature characteristics of a previously determined normal refrigerant, the saturation temperature characteristics of the refrigerant being derived from a pressure and a temperature of the refrigerant; an alerting step of, when, in the characteristics determination step, a determination is made that the saturation temperature characteristics of the refrigerant charged in the charging step are different from the saturation temperature characteristics of the previously determined normal refrigerant, issuing an alarm indicating that the charged refrigerant is different from the normal refrigerant; an inputting step of, when, in the characteristics determination step, a determination is made that the saturation temperature characteristics of the refrigerant charged in the charging step are identical to the saturation temperature characteristics of the previously determined normal refrigerant, manually inputting a type of the charged refrigerant to a data storage; a forcible prohibition step of, when the type input to the data storage is identical to a type of a predetermined refrigerant different from the previously determined normal refrigerant, forcibly prohibiting start of operation of the refrigeration apparatus, and in the characteristics determination step, a temperature detected by an outside temperature sensor that measures an outside temperature is used in derivation of the saturation temperature characteristics of the refrigerant as the temperature of the refrigerant.