PURPOSE: To reinforce an excavated hole wall by pressing it and providing a covered layer with an excavated earth given under pressure when excavating it and pulling up an earth auger by means of barrels for pressing the excavated hole wall interposed at required points on the axis of the earth auger.

CONSTITUTION: Barrels 12 for pressing an excavated hole wall are interposed at required points on an auger screw of an auger machine 6 mounted slidably on a guide 5 along a leader 3 to form an excavated hole under ground. At this point, the barrels 12 having a notch section 17 provided inclined to the axis thereof presses excavated earth against an excavated wall to form a covered layer by coating. Thus, the excavated hole wall is reinforced. A part of mud passes through the notch section 17 of the barrel 12 rising through a torque tube 10 with a screw. When pulling up the auger, each barrel 12 gives a pressure the excavated hole wall 25 again.