The objective of the present invention is to use brightness images acquired under different energy conditions to estimate the size of a defect in the depth direction in a simple manner. A charged-particle beam device according to the present invention determines the brightness ratio for each irradiation position on a brightness image while changing parameters varying the signal amount, estimates the position of the defect in the depth direction on the basis of the parameters at which the brightness ratio is at a minimum, and estimates the size of the defect in the depth direction on the basis of the magnitude of the brightness ratio (see FIG. 5).