To simply remove the sediment pushed up along a spiral blade by forming the upper face of the spiral blade into an inclined face so that the outside becomes gradually lower in the erected state of a boring rod.

A spiral blade 3 is formed into an inclined face 3a so that a portion stretched to the side becomes gradually lower. The inclination angle A is set to 15-30° for normal sediment. Baffle members 5 are provided at proper intervals on a boring rod 1. The baffle members 5 are formed into a triangle pole shape and are fixed along the axial direction to the side face section of a tube shaft 2 at the interval sections D of the spiral blade 3. The sludge (sediment) generated by the excavation of the ground at the time of execution is gradually sent upward by the spiral blade 3 and is discharged to the outside of a hole. The movement of the sediment is hindered by the baffle members 5 at this time, and the sediment stuck to the tube shaft 2 is raked off. The sediment reaching the outside of the hole drops off to the side along the inclined face 3a, thereby the sediment stuck to the boring rod 1 can be easily removed.