A tobacco filter manufacturing apparatus for making filter rods added with additives therein. A length of filter material is held between a conveyor system and a mask ring to be fed into a predetermined direction. The conveyor has laterally extending air permeable sections and air non-permeable sections; the mask ring has laterally extending slits and mask sections between the slits. The air permeable sections of the conveyor and slits in the mask ring are set in registry with each other. The conveyor and mask ring are synchronously driven. Within the mask ring is provided an additive supplier while the conveyor is provided with a negative pressure source such that the additive is adsorbed through the slits onto the filter material under the negative pressure behind the filter material through the air permeable sections of the conveyor.