Disclosed is a degassing apparatus. The degassing apparatus includes a dissolved gas extracting nozzle that extracts dissolved gases in a form of bubbles from a treatment solution including the dissolved gases, a first tank that separates the bubbles extracted while passing through the dissolved gas extracting nozzle from the treatment solution, and a second tank having a stabilization space, in which the treatment solution, from which the bubbles have been separated, is stored from the first tank and is stabilized. The dissolved gas extracting nozzle is configured such that a diameter of an outlet is smaller than a diameter of an intermediate passage such that the dissolved gases in the treatment solution are extracted in the form of the bubbles through a cavitation phenomenon.