PURPOSE: To raise the efficiency of carrying out muck by providing a rotary frame having a cutter pivotally supported in a rocking manner on its lower part to a cylinder having an endless bucket for carrying out muck inside and a scraper and a screw for raking much on its lower part.

CONSTITUTION: A pit excavator consists of an annular rotary frame 1 having a smaller diameter than that of a pit 6 and capable of freely fixing to the inner wall of the pit, a cutter boom 2 attached to the lower part of the frame 1 in a rocking manner, and a non-turning bucket elevator 3 having the frame 1 in vertically movable manner on its outside, an endless bucket 24 in a vertically movable manner in its inside, and a scraper 4 and a screw 5 for raking muck on its lower part. The muck on the bottom of the pit can thus be discharged with good efficiency.