A locking device (20,21) for an anchor rod (2) of an anchor system of a concrete wall form, has a screw nut element for screwing the anchor rod through a screw thread of the screw nut element. A dome plate can be fastened to a back of a form element (5,6) of the concrete wall form by means of fastening elements (30) and has a spherically shaped plate section with an opening in which the screw nut element is arranged so as to have radial play. The screw nut element has a groove-type radial seat which accommodates the edges of the opening in the spherical plate sections.