The invention relates to a method for continuously deaerating a liquid. The method comprises the step that the liquid is led into a closed container (1) so that a liquid surface (7) is formed within the container (1). The space above the liquid surface (7) is under vacuum. The method further includes the step that a gas is led into the liquid at a level below the liquid surface (7). The invention also relates to an apparatus which comprises a closed container (1). The container (1) has an inlet (5) for the liquid which is to be deaerated, as well as an outlet (6) for the liquid which has been deaerated, both placed in the lower region of the container (1). The container (1) further has a connection (13) to a vacuum pump (14) placed in the upper region of the container (1), as well as an inlet (15) for a gas placed in the lower region of the container (1).