PURPOSE: To cut-off water leakage of a concrete construction.

CONSTITUTION: A chemical resisting filter 3 is inserted into a gap 2 of a concrete construction 1 from the surface thereof, a through-hole 4 is bored near the gap 2, and sealing compound having slag fine-grain cement for the main body is injected from the through-hole 4. The sealing com-pound is poured into the gap 2 by water pressure of water leaked from the gap 2 and is accumulated in the filter 3 to fill into the gap 2.