PURPOSE: To make it possible to eliminate such a situation that one point turning wheel is not turnable just because only a driven wheel comes to a ground in a two wheel-concrete cutter which comprises a drive wheel and a following wheel and prevent the one point turning wheel from running up when passing on a projected surface and further prevent harmful effects, produced by housing failure of the one point turning wheel after the turning operation is over in a rising/driving lever of the one point turning wheel.

CONSTITUTION: A one point turning wheel 1 of single wheel driven by a one point turning wheel drive motor 2 is so arranged as to overlap with a side view front wheel 6. When the operator loosens his hold of the one point turning operation lever L after turning operation, it returns to the neutral stage and then resets in the stage which retracts the one point turning wheel 1.