Abstract: In a fluid filter device particularly suited for installation in an automotive power steering system, a cylindrical filter element which is axially movable in a casing having inlet and outlet passages at its opposite ends includes a foraminous side wall constituting a primary filter and a valve member at one end of the filter element normally urged to engage a seat about the opening of the inlet passage by a spring acting on the filter element so that, when the primary filter becomes clogged, the buildup of the differential pressure between the inlet and outlet passages causes axial movement of the filter element for unseating the valve member and permitting the fluid to bypass the primary filter through an annular clearance between the latter and the casing wall, and a secondary filter annulus extends from the filter element across such annular clearance for filtering the fluid which bypasses the primary filter.