To provide a device for preventing spread of fire, capable of improving workability for providing easiness and economicity in movement and assembly and speediness until really forming a fire-proofing curtain, and of arbitrarily selecting a lateral direction and the direction of the height for forming the fire-proofing curtain.

The suitable amounts of take-up devices 1 for an incombustible sheet having arbitrary width and length, balloons 11, which is reduced at ordinary time, and gas cylinders 17 are carried in and installed at a leeward position after arrival at the job site. A carabiner type one-action hook 16 is connected on the top end of an incombustible rope for hanging the incombustible sheet from a joint ring 3 of the incombustible sheet 2 and the balloons, gas charging ports 13 of balloons and gas cylinder discharging ports 19 are fitted, valve handles 18 of cylinders are turned in an opening direction and gases are injected to a prescribed pressure. Thus, the balloons 11 added with buoyancy are floated at a dash, the incombustible sheet 2 is fed out of the take-out device 1 and the fire-proofing curtain is formed in an extremely short time so that the spread of a fire can be prevented.