The aim of the invention is to connect a nebulizer to a breathing air tube of a respirator. This aim is achieved by a nebulizer-connecting device that has a breathing air-directing unit that is provided with a first mechanism for connecting a duct supplying breathing air, a second mechanism for connecting a duct evacuating breathing air, and a third mechanism for connecting the nebulizer, and a sealing unit which is arranged on the third connecting mechanism and by which a flow path for an aerosol generated by the nebulizer can be unblocked when the nebulizer is connected while the flow path for an aerosol generated by the nebulizer can be sealed therewith when the nebulizer is removed. A sealing member is opened when the nebulizer is connected while being closed when the nebulizer is removed.