A device for implanting endoprostheses has a tubular outer body and an elongated core element placed inside of the outer body. To operate the device, both the core element and the tubular body are provided with handles at their proximal ends. In order to produce a form-locking connection between the endoprosthesis and the core element, the core element exhibits a region in which is impressed a stamping corresponding to the inner form of the endoprosthesis. As a result, there are a great number of form-locking meshing sites between the enclosed, folded endoprosthesis and the core element. A device with this type of design permits a partially released endoprostheses to be folded back up in a radially contracted state again by pushing the tubular body forward so that the endoprosthesis may be repositioned. In addition, sure and reliable operation is achieved by this type of stamping of the core element.