EXCAVATING TOOL

An excavating tool of the present invention includes a casing pipe that forms a cylindrical shape about an axis line and in which a stepped portion whose inner diameter is decreased by one step is formed in an inner peripheral portion of an distal end; an inner bit where a contact portion which can come into contact with the stepped portion is formed in an outer periphery, which is inserted into the casing pipe from a rear end side in the direction of the axis line, and whose distal end portion protrudes from a distal end of the casing pipe; an engagement convex portion that is disposed on the outer periphery of the distal end portion of the inner bit so as to be retractable; a ring bit that forms an annular shape and is arranged around the distal end portion of the inner bit protruding from the distal end of the casing pipe; and an engagement concave portion that is formed in an inner peripheral portion of the ring bit. The ring bit is rotatable around the axis line integrally with the inner bit in a rotating direction during excavation, and the ring bit is locked so as not to be pulled out to the distal end side in the direction of the axis line in such a manner that the engagement convex portion protrudes to an outer peripheral side and engages with the engagement concave portion. The ring bit can be pulled out to the distal end side in such a manner that the engagement convex portion is retracted to an inner peripheral side.