EXCAVATING TOOL

PROBLEM TO BE SOLVED: To prevent the concentration of excess excavation load to the shaft section, etc., of a diameter-expanding bit in an excavating tool with the diameter-expanding bit. SOLUTION: A plurality of diameter-expanding bits 4 capable of being rotated around shaft sections 18 at intervals among the shaft sections 18 and the axis O of a device 3 are installed in the circumferential direction at the front end sections 7 of the device 3 being turned around the axis O while receiving striking force in the direction of the axis O, and the diameter-expanding bits 4 are revolved in the direction that outside diameters from the axis O are expanded with rotation to the T side in the direction of the excavation rotation of the device 3, and positioned by abutting the diameter-expanding bits 4 against the wall sections 8B of recessed sections 8 formed to the device 3. Pilot bits 5 are mounted on the axes O of the front end sections 7 of the device 3 so as to be projected to the front end sides from the diameter-expanding bits 4, and it is desirable that the outside diameters of the pilot bits 5 are set at values larger than intervals in the radial direction among the inner circumferential ends of the diameter-expanding bits 4 and the axes O.