The invention relates to a backflush device (6) for a filter system (1) for removing impurities from a fluid, the backflush device (6) serving to backflush a filter body (3) in the filter system separating the clean side (5) from the inlet side (4), and comprising at least one backflush nozzle (7) for applying a rinse medium to the filter body (3), said nozzle comprising at least one opening (8) through which the rinse medium flows in a flow direction (9) during backflushing and exits the backflush nozzle (7). In order to improve the effectiveness of the backflushing, the at least one opening is designed as a slit opening (8) extending transverse to the flow direction (9) in a straight line having a constant cross-sectional profile (16) comprising a nozzle segment (17) expanding the flow direction (9).