PURPOSE: To automatize a wedge driving work and wedge pulling work by providing a change-over means which moves a rod with its changing over to a driving percussion position and pulling percussion position.

CONSTITUTION: A percussion piston 16 is freely slidably fitted to a cylinder like machine body 10 at a constant stroke, a wedge pulling rod 18 is freely slidably fitted to this piston 16 and a driving percussion part 18b on which one end part 16b of the piston 16 is abuttable is formed at one part of this rod 18. Moreover the cylinder part 23a of a changing over means 23 is connected to the other part of the rod 18 and a pulling percussion part 23b on which the other end part 16a of the piston 16 is freely abuttable is formed at the lower end of this cylinder part 23a. The rod 18 is then moved with its changing over by a changing means 23 to a driving percussion position and pulling percussion position. At this driving percussion position the driving of the wedge is performed with the driving percussion of the rod 18 by the one end part 16b of the piston 16. At the pulling percussion position, moreover, the wedge pulling is performed with the pulling percussion of the rod 18 by the other end part 16a of the piston 16.