Abstract: Pressing device for the relative axial movement of two parts, which are arranged coaxially with respect to one another and are moveable relative to one another only by means of a high pressing power, such as for example collet chucks or sleeves, into corresponding bores of tool or collet chuck holders. The device has an outer housing which coaxially surrounds the parts which are to be pressed and which can be swung open along an axial plane. Half-inserts can be inserted into said outer housing, which half-inserts comprise in each case two fixed plates with engagement edges for the engagement on one of the parts which are to be pressed, and an axially moveable pressure plate with an engagement edge for the engagement on the second part which is to be pressed.