PURPOSE: To shorten the period of construction as well as reduce the cost of construction by a method in which a rectangular one unit is formed by excavating the ground by a multiple shaft auger, excavated soil is mixed with solidifying agent with stirring, and stress materials are penetrated to form a sheathing wall.

CONSTITUTION: The ground is excavated with stirring by means of an excavating blade 2 and a stirring blade 3 by turning the excavating shafts 1 of a multiple shaft auger. The ground is cut by the cutter blade 5a of a cutter 5 loosely fitted into the excavating shaft 1 to form a rectangular pit. The device is pulled up while injecting a solidifying agent, e.g., soil cement, etc., from nozzles 4 at the tip of the shaft 1 of the auger and also stirring the soil by the blade 3, and stress materials, e.g., H-shape steels, etc., are erected to form one unit. In the same way, each unit is mutually lapped in order to form a given column line type sheathing wall.