To inspect defects of an opening of a contact hole which is small in opening diameter, for example, not more than 0.05 μm in diameter, and high in aspect ratio, for example, ten to fifteen with high throughput.

An opening angle control lens 33 controls the opening angle of an electron beam EB incident on a wafer sample 32 to be a small value, for example, 10-5 to 10-6 rad. in an interlocking manner with an objective lens 38. The electron beam EB to be controlled in opening angle by each lens is scanned on a sample 32 by an upper stage deflector 35 and a lower stage deflector 36, and the deflection is effected in two stages so as to effect the vertical scanning of the surface of the wafer sample 32. The secondary electron generated through the irradiation of the electron beam on the sample 32 or reflected electron is detected by a detector 37 arranged in the vicinity of a rear focus of the objective lens 38.