To promote destruction of upheaval even when the ground to be digged is particularly hard to improve effect on the whole.

This excavator is provided with a frame, at least one set and a pair of rotary excavation tools having substantially the same rotary shafts, and a support assembly 32 fixed to the frame while supporting the pair of excavation tools rotatably and having an end part 32a extending between the tools of the pair of excavation tools while opposing to a cutting face. It is further provided with at least one means 54 attached to the support assembly 32 to inject ultrahigh pressure liquid 56 toward the cutting face between operation regions of the pair of excavation tools to destroy upheaval formed on the cutting face between the operation regions of the pair of excavation tools.