PURPOSE: To enable accurated installation, by providing a moving frame on a jack frame so that a very heavy body is placed on the moving frame and by supporting these frames on curved surface seats 3, 4 at a high level to enable the positioning of the very heavy body.

CONSTITUTION: A jack means is provided on an upper frame 2 fitted with curved surface seats 3, 4 on a lower frame 1. A moving frame 15, on which a projecting part 18 provided on an end of a very heavy body on which a large structure is to be installed, can be horizontally displaced on a slide 13 over a jack frame 12 by a cylinder 14. The frame 12 is vertically moved by a motor 6 through a screw 11. Since the upper frame 2 which supports the driving section of the motor 6 and the screw 11 can be moved back and forth by the curved surface seats 3, 4 the very heavy body can be lifted at an installation place by a plurality of means and be easily positioned in a horizontal direction.