A locking device 21 for an anchor bar 2 of an anchor system of a concrete wall formwork has an annular sealing element 15 for sealing off an anchor penetration hole 13 in the formwork facing 7 and a threaded nut element 24 for threading the anchor bar 2 into a threaded nut thread of the threaded nut element. A tubular guiding device 45 is flush with the threaded nut thread of the threaded nut element 24 on the end of the threaded nut element 24 to be located at the concrete formwork side. The sealing element 15 has an elastic rubber inner sealing ring 46 and the free end 51 of the guiding device 45 to be located at the formwork element side is sealingly inserted with the inner sealing ring 46 into the sealing element 15.