PURPOSE: To make it possible to readily fix objects top a surface plate made of non- magnetic material and fix objects subject to be badly affected by a magnetic field to a surface plate and romove them by providing a captioned device with one or more or pressure reducing chamber capable of air tight contact with objects to be fixed and to which other pressure reducing chambers connect.

CONSTITUTION: In fixing a workpiece 13 on a surface plate 12, turnings of the knob 5 of a fixing device A rotates a valve rod 9 making a valve 4 take an opening or closing position. And when the fixing device A is placed with the valve 4 closed and the O ring 3b brought into contact with the surface plate 12 the workpiece 13 is pushed to the O ring 3a of the device A, and the valve 4 is opened after starting of a vacuum pump 14, the air of pressure reducing chambers 2a and 2b is sucked to the vacuum pump 14 through paths 8a and 8b, a path 8, and a tube 6 reducing the pressure of the pressure reducing chambers 2a and 2b, the fixing device A, the surface plate 12, and the workpiece 13 are pushed to each other by atmospheric pressure, and the O rings 3a and 3b are so pressed hat the junction surfaces B of the device A are pressed and fixed to the surface plate 12 and workpiece 13. Even objects made of non-magnetic material or members subject to be badly affected by a magnetic field can, therefore, be readily fixed and removed.