PURPOSE: To break a pillar-row underground wall without being affected by soil and water pressures by a method in which soil cement piles are broken while guiding an auger at the center of the piles by a pilot guide hole provided at the center of the soil cement pile.

CONSTITUTION: While the pilot blade tip 14 of an auger machine is guided toward a pilot guide hole 16 drilled at the center of a sol cement pile 9, an underground wall built by a pillar row constructed of the soil cement piles 9 is broken. The underground wall can therefore be broken without being affected by the surrounding soil pressure and water pressure and the passage of the underground water is allowed.