Abstract: The present invention relates to a method for preparing a carbonate salt. The method for preparing a carbonate salt can provide a useful material by implementing a carbon dioxide capture method via a capturing agent such as ammonia with an electrolytic device to produce a carbonate salt, and thus capturing carbon dioxide from the atmosphere. Further, the preparation method may purely produce a carbonate salt without generating by-products using electric energy, and at the same time, the capturing agent may be reused without any additional process. Furthermore, the preparation method may selectively provide a carbonate salt in the desired form by adjusting the pH of a solution containing the carbonate salt using the electrolysis of water.