Abstract: The automatic adjusting device for a sighting system of a device which can be directed to a target, the automatic adjusting device having an autocollimator, comprising a light source, a splitter cube and an objective. The autocollimator generates an illuminated spot on a detector associated with the splitter cube. A tilting of a mirror secured to the device which can be directed to a target leads to a displacement of the illuminated spot, which displacement is convertible into electrical signals for the automatic adjustment of the sighting system. A prism which is invariant with respect to tiltings is disposed in the beam path of the autocollimator. This prism deflects the autocollimation beam path into a sighting system objective in such a manner that a virtual is generated in an intermediate image= illuminated area image plane of the sighting system objective outside its beam path.