A mounting unit for a tool depositing device includes a coupling carrier having a tool-side coupling element, in particular for a coupling device for a tool of a robot, and a holding device that can be connected to a mounting plate of the tool depositing device. An intermediate space is provided between the holding device and the coupling carrier to allow compensating movements between the coupling carrier and the holding device. The holding device includes two guide rails, between which the coupling carrier is pushed in. An interlocking engagement between the coupling carrier and the guide rails is produced by engaging at least one protuberance in at least one recess, wherein the at least one recess and the at least one protuberance are arranged on mutually opposing sides of the coupling carrier and of the guide rails.