PURPOSE: To easily and economically excavate a vertical hole, for which positioning to the ground and direction of excavation are precisely controlled.

CONSTITUTION: A guide device 1 for setting excavating position for a vertical hole with an opening allowing a wall surface protection drum 2 to be inserted therein provided and a plurality of sliding contact plates available for contacting with the outside of the wall surface protection drum 2 provided to the inside of the opening with capability of adjusting positions provided is set on the surface of the ground. Then, the wall surface protection drum 2 is erected on the guide device 1 for setting excavating position for the vertical hole so that the lower end thereof can be inserted into the opening of the guide device, and the sliding contact plates are brought into contact with the outside of the wall surface protection drum 2. While the wall surface protection drum 2 is pressed into the ground, earth inside the wall surface protection drum 2 is removed after excavation is made with an excavator 3.