To sufficiently bear the reaction despite of a light-weight working machine by providing a tightening material composed of an elastic material to an opening edge of a cup main body having the bottom face opened and by supporting a plurality of suction cups connected to a vacuum pump with intake ports provided in the cup main bodies in such a state as raising/lowering to a base board.

Extension legs 11... composed of hydraulic cylinders are vertically projected to the tips of left/right outriggers provided in the front/rear both ends in a base board 2 and suction cups 12 are attached to the bottom ends of rams of respective extension legs 11.... The suction cups 12 are fixed to the bottoms of the extension legs 11... with their openings faced to the bottom and a vacuum pump is connected to the intake ports provided in their appropriate positions. The cup main body opening edge of the suction cup 12 has an elastic tightening material coveringly attached thereto. In working, the respective suction cups 12... are grounded on a pavement surface and when the vacuum pump is driven so as to suck the air in the respective cups 12..., the suction force of the respective cups 12... can bear the reaction and the pavement board whole body.