Abstract: The invention relates to a holding device (2) for holding a magnetizable substrate (8) during machining of at least one substrate surface, in particular of a magnetizable tool to be machined, comprising a magnetic holding unit (4) arranged at the end for fixing the substrate (8) at the end by forming a magnetic field, a receiving unit (6) arranged on the holding unit (4) for receiving the substrate (8), a replaceable adapter unit (10) arranged within the receiving unit (6) for guiding and shielding the substrate (8), the adapter unit (10) having at least one recess (12) for the feedthrough of the substrate (8), the substrate (8) being fixable within the holding device (2) in a laterally supported manner by means of the recess (12).