A carbonation device comprising: a storage tank storing a carbonation subject solution; a droplet spray unit spraying the carbonation subject solution from the storage tank in droplets; a carbonation reaction tank connected with the droplet spray unit, filled with a carbonation gas under a predetermined pressure and providing a slurry by a carbonation reaction of the droplet-sprayed carbonation subject solution with the filled carbonation gas; a carbonation gas supply unit supplying the carbonation gas into the carbonation reaction tank to maintain the carbonation gas in the carbonation reaction tank under the predetermined pressure; and a slurry outlet unit ejecting the slurry from the carbonation reaction tank to maintain the slurry formed in the carbonation reaction tank within a predetermined level, wherein an alkali solution input unit adjusts the pH of the slurry formed in the carbonation reaction tank; wherein the alkali solution input unit comprises: a pH measuring unit measuring the pH in the carbonation reaction tank; an alkali solution input pump supplying an alkali solution into the carbonation reaction tank according to the pH measured by the pH measuring unit; and an alkali solution input nozzle connected to the alkali solution input pump and inputting the alkali solution into the carbonation reaction tank; wherein the carbonation gas supply unit and the alkali solution input unit are connected to the carbonation reaction tank. a storage tank storing a carbonation subject solution; a droplet spray unit spraying the carbonation subject solution from the storage tank in droplets; a carbonation reaction tank connected with the droplet spray unit, filled with a carbonation gas under a predetermined pressure and providing a slurry by a carbonation reaction of the droplet-sprayed carbonation subject solution with the filled carbonation gas; a carbonation gas supply unit supplying the carbonation gas into the carbonation reaction tank to maintain the carbonation gas in the carbonation reaction tank under the predetermined pressure; and a slurry outlet unit ejecting the slurry from the carbonation reaction tank to maintain the slurry formed in the carbonation reaction tank within a predetermined level, wherein an alkali solution input unit adjusts the pH of the slurry formed in the carbonation reaction tank; wherein the alkali solution input unit comprises: a pH measuring unit measuring the pH in the carbonation reaction tank; an alkali solution input pump supplying an alkali solution into the carbonation reaction tank according to the pH measured by the pH measuring unit; and an alkali solution input nozzle connected to the alkali solution input pump and inputting the alkali solution into the carbonation reaction tank; a pH measuring unit measuring the pH in the carbonation reaction tank; an alkali solution input pump supplying an alkali solution into the carbonation reaction tank according to the pH measured by the pH measuring unit; and an alkali solution input nozzle connected to the alkali solution input pump and inputting the alkali solution into the carbonation reaction tank; wherein the carbonation gas supply unit and the alkali solution input unit are connected to the carbonation reaction tank.