An ammonia/CO2 refrigeration system is provided in which the ammonia cycle and CO2 brine cycle can be combined without problems even when refrigeration load such as refrigerating showcase, etc. is located at any place in accordance with circumstances of customer's convenience. The system comprises apparatuses working on an ammonia refrigerating cycle, a brine cooler for cooling and condensing CO2 by utilizing the latent heat of vaporization of the ammonia, and a liquid pump provided in a supply line for supplying the cooled and liquefied CO2 to a refrigeration load side cooler, wherein said liquid pump is a variable-discharge pump for allowing CO2 to be circulated forcibly, and the forced circulation flow is determined so that CO2 is recovered from the outlet of the cooler of the refrigeration load side in a liquid or liquid/gas mixed state.