PURPOSE: To provide such a device that prevents a lifting wire from coming into contact with the frame of a house, impeding its operation at a time when equipment is conducted into the dustproof house via this lifting wire by means of heavy machinery as well as to enable it to dispense with a job for sheet removal after the termination of works and also to net a scaffold in the house easily.

CONSTITUTION: A pair of guide rails 3 are set up in the upper end of a frame 2, and each of both the ends is sufficiently projected out of this frame 2. Then each end of plural roof frames 4 is guide to the guide rails 3 free of movements, and these roof frames 4 are covered with a roof surface sheet 5. In addition, flat U-shaped fittings 10 are attached to each pedestal 1 of the frame 2 free of detachment, whereby a scaffold is clamped free of detachment via each flange 10a of these fittings 10.