A waterproof sheet which comprises a base layer constituted of a silicone rubber and a pressure-sensitive adhesive layer superposed thereon and which is for use in preventing the infiltration of rainwater, etc., characterized in that the pressure-sensitive adhesive layer is constituted of a cured object of an addition reaction type curable silicone composition in which the theoretical amount of crosslinks is 0.005-0.01 mol/g and the ratio of the amount of SiH groups to the amount of alkenyl groups, SiH/alkenyl, is 0.5-1.1 by mole and which, when cured, has a hardness as measured with a CSR-2 type hardness meter of 3-20. This waterproof sheet can be used over a long period without decreasing in physical property, and has waterproofing properties over a long period. In particular, by delimiting the hardness and adhesive force of the pressure-sensitive adhesive layer, the waterproof sheet can be made to withstand long-term use. The waterproof sheet exhibits excellent durability concerning pressure-sensitive adhe
