PURPOSE: To enable the easy and safe execution of putting substrates into and out of a preliminary chamber by providing plural pawls bent inward at the front ends on the rear surface of the cap in the aperture of the preliminary chamber of a vacuum treating device.

CONSTITUTION: The pawls 11 which are smaller in the distance between the front end bent parts 13 than the width of the substrate 9 and are larger in the distance between the pawls 11 than the width of the substrate 9 are mounted on the rear surface of the cap 6 of the upper aperture 12 at the time of putting the substrate 9 to be subjected to various kinds of the surface treatments into and out of the preliminary chamber 2 connected to a vacuum treating chamber 1 from the upper aperture 12 by a gate valve 3. The treated substrate 9 imposed on link type forks 8 in the preliminary chamber 2 is supported with the bent parts 13 of the pawls 11 by rising the cap 6 of the aperture 12 of the preliminary chamber and are easily taken out of the aperture 12 without requiring manual labor. The fresh untreated substrate is safely and easily put into the substrate 2 and is carried into the vacuum treating 1 via the gate valve 3 through the narrow aperture 12 without requiring manual labor by utilizing the cap 6 provided with the pawls 11 even in the case of admission of this substrate into the preliminary chamber 2.