To execute boring without rotating bits at the time of boring, prevent heat of rods, reduce damage and abrasion of the rods and bits, and decrease noise, in an impact device utilizing an impact action caused by an ultra- magnetostriction element.

This impact device 10 is provided with a bit part 40 arranged a plurality of rods 34 attached a tip 33 on tops of them at predetermined intervals, and a plurality of impact generating parts 20 provided so that an impact is given to a plurality of rods 34 by ultra-magnetostriction elements 5 in which an ultra-magnetostriction material 4 is arranged at a center of an exiting coil 3 applied pulse voltages. The impact is independently given to each rod 34 by each ultra-magnetostriction element 5 corresponding to them through rods 11 and intermediate rods 19. Accordingly, rock, etc., are crushed by the tip 33 of the tops of rods, so that crushing is performed over whole area of the bit part 40.