PURPOSE: To reduce a wall thickness remarkably by arranging cushion materials in joints of arc wall bodies, in forming an annular underground continuous wall by depositing and connecting multiple arc wall bodies to each other.

CONSTITUTION: Multiple annular unit wall bodies 1a, 1b,... 1n driven into the ground are connected to each other through partition boards 3 to construct an annular underground continuous wall. In this case, reinforcement cage 4 is jointed to the board 3, and a cushion material 4 is stamped integrally on the board 3. Thus a wall thickness can be reduced by approx. 30% because the cushion material absorbs an axial force in circumferential direction, and also this can be worked easily at low cost without changing the conventional work method.