PURPOSE: To ensure good workability and keep follow-up quality for cut-off function and deformation, regarding a joint construction method for a temporary sheet-pile cofferdam construction method.

CONSTITUTION: Regarding a temporary sheet-pile construction cofferdam method, right and left opposite steel tube piles 1, 1, 1 and 1 driven at a joint position P are coupled to one another via engagement pieces 2, 2a, 2 and 2a, and gaps S and S in the pieces 2 and 2 are filled with elastic materials 3 and 3. On the other hand, guide plates 4, 4, 4 and 4 are projected from the tube piles 1 and so forth toward space W thereby formed, in such a way as faced to one another in right and left, and front and rear directions. Also, the right and left opposite sheathing boards 6 and 6 laid along the guide plates 4 and so forth are inserted to the prescribed depth. A cut-off rubber 8 is laid between the boards 6 and 6, and space W formed out of the front and rear piles 1 and so forth is charged with two fills 12 and 12 of concrete, thereby causing the boards 6 and 6 to come in close contact with the plates 4 and so forth.