PURPOSE: To provide a water stop sheet having excellent weather resistance, chemical resistance, heat resistance, cold resistance, breaking load, sealing property, softness, durability, and workability at the time of execution.

CONSTITUTION: A multilayer sheet has a three-layer structure consisting of an intermediate layer and two outer layers. The intermediate layer is made of a composition (A) in which 90wt.% or below of polyethylene (1) having a density of 0.940-0.965g/cm3 and 10wt.% or above of thermoplastic resin (2) having a torsional modulus of rigidity (JIS K6730) of 400kgf/CM2 or below are mixed. Each of the outer layers is made of a composition (B) in which 10-30wt.% of polyethylene (3) having a density of 0.940-0.965g/cm3 and 70-90wt.% of thermoplastic resin (4) having a torsional modulus of rigidity (JIS K6730) of 400kgf/cm2 or below are mixed, and has a sheet breaking load of 30kgf/cm or above.