A mounting device for mounting a length measuring system extending in a measurement direction, the mounting device including a basic body, a steadying device attached to the basic body and a retainer attached to the basic body. A length measuring system that extends in a measurement direction is fixable on the basic body by clamping between the steadying device and the retainer, wherein the basic body and the retainer are embodied for guiding the retainer on the basic body longitudinally in a manner fixed against relative rotation in a direction of the steadying device by an adjusting element.