To enable a wheel chair to easily get over a back plate under condition of not interfering storage of the back plate in a storage part of a ceiling when hoisting a curtain body without changing the shape of the back plate.

A fireproof screen shutter comprises: a fireproof screen 12 having an escape door 16; a back plate 20 having a back plate step portion 50, reaching a floor when the screen 12 is lowered and stored in a storage part of a ceiling when the screen 12 is hoisted; a step forming member 62 provided on the back plate step portion 50 so as to be changeable to a storage state where it is stored on the back plate step portion 50 and a spreading state where it spreads on the floor, and capable of being stored along with the back plate step portion 50 in the storage part of the ceiling and forming a step, which is lower than the back plate step portion 50, between the back plate step portion 50 reaching the floor and the floor in the spreading state; a spreading mechanism 60 provided on the back plate 50 and changing from a stand-by state where a part thereof projects downward from the bottom part of the back plate 50 to an operation state which changes the step forming member 62 from the storage state to the spreading state when a part thereof reaches the floor.