A filter device has a first connection (A1) to a hydraulic working circuit, an associated filter element (F1) and an additional connection (A2) by which leakage oil amounts of hydraulic components can be fed. A control apparatus (V2) can feed the leakage oil amounts from the additional connection (A2) to the filter element (F1) when a specified working pressure of the working circuit is not reached at the first connection (A1).