To accurately adjust the center of a hole of a base of a press-fitting machine to the center of a pile by mounting three bridge parts on a base while extending them from the center, moving the same to obtain the center of the hole of the base, and adjusting the tip of an indication rod in the perpendicular direction to the pile center.

A receiver for a ball 7 through which an indication rod 4 having a weight 6 mounted thereon passes is provided at the center where one end of each of three bridge parts 3 is disposed so that they extend radially therefrom. The other end of each of the parts 3 is placed on a base of a casing tube press-fitting machine, and moved. The distances of the three bridge parts 3 are made equal from the center in this way to obtain the center position of the hole provided in the base. The press-fitting machine is moved to adjust the tip of an indication rod 4 to which the weight 6 indicating the center of the hole of the base is mounted to the center of a pile on the ground. Accordingly, according to operation, the press-fitting machine can be set at a safe and accurate position.