an apparatus for reducing the amount of carbon dioxide released into the atmosphere by fixing and dumping carbon dioxide which is disposed in seawater or fresh water satisfying certain temperature and pressure conditions for the formation of carbon dioxide hydrate or its clathrate comprising : a ) a transport pipeline equipped with a compressor ; b ) a carbon dioxide source connected to said transport pipeline upstream of said compressor ; c ) a plurality of ejector nozzles disposed at one end of the pipeline ; d ) a reaction housing which allows seawater or fresh water and carbon dioxide to react with each other and form the carbon dioxide hydrate or its clathrate ; e ) a dispersing propeller ; wherein the reaction device is provided with the ejector nozzles and the dispersing propeller at the inlet portion of the device ; the concentration of the carbon dioxide is supplied into the pipeline and is discharged by the compressor into the reaction housing from the ejector nozzles under pressure to form the carbon dioxide hydrate or its clathrate ; the thus produced hydrate or its clathrate is dispersed by the propeller out of the reaction housing to the deep bottom of the sea .