An object of the present invention is to provide a technique for efficiently sequentially fracture around the multiple of drilling that has been pre-formed to be crushed, such as rock and rock.
SOLUTION: In the crushing method of crushing the periphery of the multiple of drilling 6, and the drilling forming step of forming a plurality of drilling 6 to be crushed 5, the tip end surface of the outer diameter smaller than the inner diameter of the drilling 6 the chisel 3 having a tip portion 32 inclined surface 32a having an outer diameter becomes larger outer diameter than the inner diameter of the larger it becomes drilling. 6, 32 b are formed in accordance with the procedure goes to the rear end side from the distal end side and having a plurality of cutting at least two drilled 6 tip portion 32 is inserted into the inclined surface 32a, the state in which 32b is separated from the percussion device 2 to make a striking force to the abutment with and chisel 3 the inner wall of the drilling 6 of the hole 6 a chisel installation step of installing in, by sequentially applying a striking force by the percussion device 2 to the rear end face of the chisel 3 installed in drilling 6, a crushing step of crushing the periphery of the drilling 6 in the crushed 5 , equipped with a.
.FIELD 7