To minimize the time overhead for mechanical X-Y stage movement.

In this defect detecting method, defects on a substrate are detected by a process for positioning an charged particle beam optical column 600, which has a field of view(FOV) with a resolution practically uniform over the entire column, with respect to a patterned substrate 622, a process for scanning the substrate while maintaining the optical charged particle beam column at a fixed position on the substrate, so as to capture images on the plural small areas of the substrate inside the FOV and a process for comparing the captured images with a reference image. By utilizing a large FOV image formation system, having the FOV with the resolution practically uniform all over the system, images can be captured over a wide range of the substrate without, requiring the movement of a mechanical X-Y stage 632 and time overhead for the mechanical stage movement can be reduced. In order to improve the throughput, plural columns may be linked as well.