A light beam guiding device for a tunneling machine includes a light source for emitting a beam of light, a first target, and a second target. The first target includes means for passing a light pattern to the second target which is dependent upon the position of the first target relative to the light beam. The second target includes means for indicating the location of the light pattern thereon. Proper alignment of the tunneling machine relative to the light beam is determined by a predetermined light pattern from the first target falling on a predetermined location of the second target. Each target is mounted on the tunneling machine by a mounting means, each of which includes a means to adjustably position its associated target relative to the tunneling machine to compensate for machine roll.