To provide a reverse-type shaft-excavating machine having a means which prevents drill pipe or the like from being clogged with gravels and prevents the working efficiency from decreasing.

A control part 15 preventing gravels from passing through is formed in the center shaft 5 of an excavating body. A slit 16 is formed at the side face of a lower part from the control part 15 for gravels in the center shaft 5. The front end is inserted in the center shaft or separated therefrom through the slit 16. A crushing bit 17 breaking gravels 19 accumurated in the control part 15 in the center shaft is provided. Further, an opening/closing member 11 for the slit 16 operated in an interlocking motion with the crushing bit 17 is provided.