A filling unit for a manufacturing machine for the production of disposable cartridges for electronic cigarettes; the filling unit comprises: a cylindrically shaped tank, which is arranged horizontally, is mounted rotating in a stepwise manner around a vertical rotation axis, is delimited, at the bottom, by a circular shaped base disc, and is delimited, on the sides, by a cylindrical side wall, which projects perpendicularly from the base disc; a feeding duct which has an outlet opening arranged inside the tank so as to feed a flow of tobacco to the inside of the tank, which forms a bed resting on the base disc of the tank; at least one group of seats, each obtained in the base disc and adapted to receive and contain a corresponding quantity of tobacco; a transfer device which is arranged in a fixed position in the area of a filling station and cyclically transfers the quantities of tobacco into the seats of the group that is standing still in the filling station; a shutter element, which is movably mounted, is arranged below the group of seats and is provided, for each seat, with an air-permeable plug and with a through hole, arranged beside the plug; and an actuator device which, on the outside of the filling station, keeps the shutter element in a closing position, in which a corresponding plug is arranged below each seat so as to close the seat at the bottom and prevent the descent of the tobacco, and, in the filling station, keeps the shutter element in an opening position, in which a corresponding through hole is arranged below each seat so as to allow the descent of the tobacco; the filling unit is characterized in that it comprises a cleaning device, which cleans the air-permeable plugs before the seats are filled with new quantities of tobacco. a cylindrically shaped tank, which is arranged horizontally, is mounted rotating in a stepwise manner around a vertical rotation axis, is delimited, at the bottom, by a circular shaped base disc, and is delimited, on the sides, by a cylindrical side wall, which projects perpendicularly from the base disc; a feeding duct which has an outlet opening arranged inside the tank so as to feed a flow of tobacco to the inside of the tank, which forms a bed resting on the base disc of the tank; at least one group of seats, each obtained in the base disc and adapted to receive and contain a corresponding quantity of tobacco; a transfer device which is arranged in a fixed position in the area of a filling station and cyclically transfers the quantities of tobacco into the seats of the group that is standing still in the filling station; a shutter element, which is movably mounted, is arranged below the group of seats and is provided, for each seat, with an air-permeable plug and with a through hole, arranged beside the plug; and an actuator device which, on the outside of the filling station, keeps the shutter element in a closing position, in which a corresponding plug is arranged below each seat so as to close the seat at the bottom and prevent the descent of the tobacco, and, in the filling station, keeps the shutter element in an opening position, in which a corresponding through hole is arranged below each seat so as to allow the descent of the tobacco; the filling unit is characterized in that it comprises a cleaning device, which cleans the air-permeable plugs before the seats are filled with new quantities of tobacco.