A filter device, in particular a return line suction filter, has at least one filter housing (3) receiving a filter element (17) defining a longitudinal axis. The filter element has an end cap with an enclosure at one filter element end enclosing an end edge of the filter material (39) and fixed to an element receptacle (5) connected to the filter housing (3) for fixing the location of the filter element (17) in its functional position. The element receptacle (5) and the associated end cap (21) of the filter element (17) have design irregularities (63, 65) adapted to each other at their parts (23, 47) engaging each other in the functional position of the filter element (17). The irregularities enable the engagement in a positional alignment to each other.