To retract effectively and safely a drill block, by using a laterally retracting system together with a boring system driven at the top.

The device unit 13 is guided along a guide rail by a wagon 15. A block 11 and the device 13 are held on a pipe at the center, in the boring position. A wire 17 is connected to a block 18 and a cylinder 19 is connected to the block 11 and attached to the wagon 15. The block 18 is formed of a roller 20 to change the direction of the nearest wire to the center line. Further, a skid system is arranged by guiding the roller 20 by a cylinder 22. The block 18 and the roller 20 have an effect shifting the direction of the wire from the center to a selected position by acting a pressure on the adjacent wire. When the block 11 is retracted and a space is given in a new portion, the block 11 is shifted from the center of the drill pipe to the side by the cylinder. In this way, a moment of a force acting on the guide rail is reduced and bending of the wire is prevented.