A carbonated water production unit, comprising: a coupler configured to be coupled to and decoupled from a container; a nozzle module configured to inject carbon dioxide into the container; a regulation member disposed upstream of the nozzle module and configured to regulate a supply of the carbon dioxide into the container; a first valve configured to regulate a supply of water into the container via a water supply pipe; a second valve disposed at a pressure regulation pipe through which air in the container flows and configured to regulate a pressure of the container; a water level detector configured to detect a water level of the container; a user interface configured to receive a command for production of carbonated water, an input of a concentration of the carbonated water and an input of a command for adding carbonic acid and configured to output information on the production of the carbonated water; and a controller configured to control the first valve to supply water when the command for the production of carbonated water is input, determine information on injection of the carbon dioxide corresponding to the concentration of the carbonated water when the supply of water is completed, control the regulation member to inject the carbon dioxide based on the determined information on the injection, control the second valve to regulate the pressure of the container when injection of the carbon dioxide is completed, and when the production of the carbonated water is completed and the command for adding carbonic acid is input to additionally inject the carbon dioxide into the carbonated water, the controller is configured to control opening of the regulation member and the second valve, and characterized in that when the detected water level is a predetermined water level or more, the controller is further configured to control the regulation member and deactivate an operation of the water level detector during the injection of carbon dioxide. a coupler configured to be coupled to and decoupled from a container; a nozzle module configured to inject carbon dioxide into the container; a regulation member disposed upstream of the nozzle module and configured to regulate a supply of the carbon dioxide into the container; a first valve configured to regulate a supply of water into the container via a water supply pipe; a second valve disposed at a pressure regulation pipe through which air in the container flows and configured to regulate a pressure of the container; a water level detector configured to detect a water level of the container; a user interface configured to receive a command for production of carbonated water, an input of a concentration of the carbonated water and an input of a command for adding carbonic acid and configured to output information on the production of the carbonated water; and a controller configured to control the first valve to supply water when the command for the production of carbonated water is input, determine information on injection of the carbon dioxide corresponding to the concentration of the carbonated water when the supply of water is completed, control the regulation member to inject the carbon dioxide based on the determined information on the injection, control the second valve to regulate the pressure of the container when injection of the carbon dioxide is completed, and when the production of the carbonated water is completed and the command for adding carbonic acid is input to additionally inject the carbon dioxide into the carbonated water, the controller is configured to control opening of the regulation member and the second valve, and characterized in that when the detected water level is a predetermined water level or more, the controller is further configured to control the regulation member and deactivate an operation of the water level detector during the injection of carbon dioxide.