A carbonated water production unit for a refrigerator includes a coupler to which a container is coupled to be detachable, a cylinder configured to store carbon dioxide, a nozzle module configured to inject carbon dioxide into the container, a regulation member, a first valve, a second valve, a user interface which receives a command for production of carbonated water and an input of concentration of the carbonated water, and a controller which controls the first valve to supply water when the command for the production of carbonated water is input, determines information on injection of the carbon dioxide corresponding to the concentration of the carbonated water when the supply of water is completed, controls the regulation member to inject the carbon dioxide based on the determined information on the injection, and controls the second valve to regulate the pressure of the container when injection of the carbon dioxide is completed.