PROBLEM TO BE SOLVED: To provide a sheet of a waterproof device, capable of suppressing water immersion to an indoor side.SOLUTION: A sheet of a waterproof device comprises: a sheet body 12 blocking a lower end side in the vertical direction of the opening 2 by integrally covering a specified part 41 on a lower end side in a vertical direction of an opening/closing body 4 for opening and closing an opening 2 of a structure S and a part adjacent to the specified part 41 among the structure S, and positioned to the outdoor side further than the opening/closing body 4 so that a lower end part in the vertical direction extends along a floor surface 6 toward an outdoor side, with an end in the width direction being held by a holding member 20; and a cut-off rubber 50 attached to the indoor side of an end in the width direction of the sheet body 12, over a range corresponding to the specified part 41 and a range of the lower end part in the vertical direction.
