PURPOSE: To permit operations on narrow scaffolds by a method in which a shaft tube is set around a casing and given turning forces and striking forces, and the coupler of the shaft tube is faced with a rotary wall and an excavating wall.

CONSTITUTION: A shaft tube 12 is set around a casing 20, and given a circumferential turning force by a rotary driver and also given a striking force from back to forth by a striking piston device. On the outer face of the casing 20, a wall 22A in the turning direction and a wall 22B in the excavating direction are formed, and a coupler is integrally or separately provided to the inner surface of the tube 12 in a freely appearing and disappearing manner. The casing 20 is inserted into the tube 12 and the coupler is faced the walls 22A and 22B, and steel bars, PC steel wires, or injection tube is inserted into the casing 20 for anchoring work or air-lock and bolting work.