PURPOSE: To prevent underground water from emerging and blowing out by braking a wall due to the nature of the soil and underground water pressure in a soil cement underground continuous wall created by a multishaft auger machine.

CONSTITUTION: Though core material frames formed integrally with plural H steel 1 at prescribed intervals as core materials are inserted in respective elements excavated by a multishaft auger machine, in a range necessary to shield water due to a stratum, water shielding plates 2 are stuck between H steel flanges on the floor excavating side, and connecting water shielding plates 4 and 4' projecting close up to an excavating hole circle oblique outward from the flange surfaces of both end H steel are stuck to a core material frame 7 for a preceding element. Connecting water shielding plates 3 and 3' projecting close up to the excavating hole circle along the flange surfaces of both end H steel are stuck to a core material frame 8 for a succeeding element, and an underground wall 10 where these core material frames 7 and 8 are inserted in soil cement is constructed, and after a floor is excavated, the connecting water shielding plates 4 and 4' are extended, and are welded to the connecting shielding plates 3 and 3', so that an integrated water shielding wall is constituted.