Abstract: The apparatus (1) comprises a first chamber (3) having an inlet (2) and a second chamber (23) having an outlet (24), with flow spaces disposed between the two chambers. The flow spaces are divided by a longitudinally running filter fabric (17) into an intake space (13) and a discharge space (14). The cross-section of the intake space continuously diminishes from the intake end to the discharge end, whereas the cross-section of the discharge space is smallest at the intake end and increases to a maximum toward the discharge end. Several filtering planes may be stacked about a hollow cylinder (4) forming the first chamber and run radially outward. The result is a filter apparatus in which the medium to be filtered is kept in continuous flow, and the filter fabric is optimally utilized.