Filter device having a filter housing, which comprises a connection point for supplying a flow of unfiltered medium and a further connection point for discharging a flow of filtrate, with a hollow cylindrical filter element comprising a filter material, which is connected between the respective connection points (12, 14) for filtering the flow of unfiltered medium, and with a flow guidance device for guiding the flow of unfiltered medium within the filter housing, wherein the flow guidance device is also used to guide the flow of filtrate in the filter housing and has a separating wall which, with its mutually opposing wall sides (24, 26), guides the flow of unfiltered medium, on the one hand, and the flow of filtrate, on the other hand, separately from each other while flowing against said wall sides, and through which a fluid duct passes, which opens out at the end into the interior of the filter element, on the one hand, and towards one of the two connection points (12, 14), on the other hand, wherein the flow guidance device is inserted, as an independent component, in a filter head which is connected in a releasable manner to a filter bowl with the replaceable filter element, wherein the fluid connection points (12, 14), arranged in the filter head of the filter housing, open out without deflection into a respectively assignable flow chamber (82, 84), which flow chambers are spatially separated from each other by the flow guidance device, and wherein the filter element is replaceably accommodated in the filter bowl of the filter housing, said filter bowl being closed by the filter head in the manner of a removable cover part, characterised in that the fluid duct has a hollow cylindrical duct sleeve, which is an integral part of the separating wall, which additionally has a hollow cylindrical retaining sleeve by means of which the separating wall can be fixed to cover parts (76, 108) of the filter head in which the retaining sleeve engages; and in that a gap opening connects the fluid duct to one of the flow chambers and is configured as a wedge-shaped cut-out of the retaining sleeve. wherein the flow guidance device is inserted, as an independent component, in a filter head which is connected in a releasable manner to a filter bowl with the replaceable filter element, wherein the fluid connection points (12, 14), arranged in the filter head of the filter housing, open out without deflection into a respectively assignable flow chamber (82, 84), which flow chambers are spatially separated from each other by the flow guidance device, and wherein the filter element is replaceably accommodated in the filter bowl of the filter housing, said filter bowl being closed by the filter head in the manner of a removable cover part, characterised in that the fluid duct has a hollow cylindrical duct sleeve, which is an integral part of the separating wall, which additionally has a hollow cylindrical retaining sleeve by means of which the separating wall can be fixed to cover parts (76, 108) of the filter head in which the retaining sleeve engages; and in that a gap opening connects the fluid duct to one of the flow chambers and is configured as a wedge-shaped cut-out of the retaining sleeve.