To provide a caisson cutting-edge section excavator, in which excavation operation can be automated and which can excavate soil and sand with high efficiency.

The caisson cutting-edge section excavator has a truck 3 for going-around capable of revolving along a guide rail 2 fixed onto an inner circumference in the vicinity of the cutting edge section 1a of a caisson 1 in a going-around manner and a rotary type excavator body such as an auger screw 6, a submerged load header 20 or the like being installed to the truck 3 for going-around in a manner that the excavator body can be lifted and lowered and excavating a ground in the vicinity of the cutting edge section 1a.