A variation in time of charging refrigerant into a refrigeration circuit is suppressed. A refrigerant charging device has an electric valve (49) provided in a supply pipe (47), a flow rate control section (50) for adjusting, based on a pressure difference between the pressure of refrigerant supplied to the supply pipe (47) and the pressure of refrigerant on the suction side of a compressor (14), the degree of opening of the electric valve (49) so that the flow rate in the supply pipe (47) is within a predetermined range, an outdoor air temperature sensor (36) for sensing outdoor air temperature, and a low pressure side pressure sensor (34) for sensing the pressure of the refrigerant on the suction side of the compressor (14). The pressure difference is a difference between a saturation pressure corresponding to the outdoor air temperature sensed by the outdoor air temperature sensor (36) and a refrigerant pressure sensed by the low pressure side pressure sensor (34).