To provide a water immersion suppression wall which suppresses water immersion without using buoyancy.

When a water depth exceeds dpt_L, the expression is established: [a moment of rotation M_dpt1 generated when a gravity force by a mass(L1×W×dpt) acts on a first part 201]-[a moment of rotation M_dpt2 generated when a gravity force by a mass(L2×W×dpt) acts on a second part 202]>a moment of rotation M2_s at a normal time acting on the second part 202-a moment of rotation M1_s at a normal time acting on the first part 201. Thereby, a moment of rotation M1>a moment of rotation M2, that is, the moment of rotation which is going to counterclockwise rotate a water immersion suppression wall becomes larger than the moment of rotation which is going to clockwise rotate the water immersion suppression wall. As a result, the water immersion suppression wall rotates counterclockwise and stands vertically.