To provide a deflection correcting mechanism for an excavating device capable of improving construction efficiency and facilitating deflection correction.

In the deflection correcting mechanism for the excavating device provided with a casing pipe 6 and a screw auger 10 provided in the casing and having a screw blade 12, and constituted to excavate while rotating the casing pipe 6 and the screw auger 10 reversely to each other, the spiral blade has spiral sections LS with large blade outer diameters, and spiral sections SS with small blade outer diameters, and correction members 61 abutting on the spiral blade in the spiral sections LS to correct the excavating direction are provided in two parts with a predetermined space in the longitudinal direction of the casing pipe, symmetrically with respect to the axis of the screw auger. When correcting deflection, only the casing pipe is pulled up so that the spiral sections LS abut on the correcting members, respectively, and in this state, only the screw auger is turned without turning the casing pipe to carry out a deflecting advance.