A filter device for filtering fluid, in particular an oil filter, is provided. The filter device includes a first filter medium and a second filter medium, the first filter medium having a greater filter action than the second filter medium, and the filter media being folded in pleated form and having a plurality of folds, the first filter medium and the second filter medium being connected to one another in the longitudinal direction of the folds. An easily producible and highly effective filter device is thus achieved.