PURPOSE: To correct an error in voltage readout due to differences of materials, by specifying materials by a reflected electron and correcting a secondary electron signal by using the radiation ratio of the secondary electron characteristics to the materials.

CONSTITUTION: When a sample 2 is irradiated with an electron beam 1, a secondary electron and a high-speed reflected electron are obtained from an electron beam probe point and then detected by corresponding detectors 4 and 3 to obtain a secondary-electron signal Ss and a reflected-electron signal Sr. The reflected-electron signal Sr is inputted to a determining circuit 5 for a secondary- electron radiation ratio having an incorporated coordinate table of secondary electron radiation ratios, thus obtaining the secondary electron radiation ratio. Then, the secondary-electron signal Ss and the secondary-electron radiation ratio are inputted to a dividing circuit 6, which finds a voltage at the probe point. Thus, unstable elements due to material effect are removed and the functions of an integrated circuit device are inspected accurately.