PURPOSE: To provide a secondary electron spectroscopy in which absolute value of the energy of secondary electrons emitted from a sample can be determined accurately.

CONSTITUTION: In a sample chamber 8, a sample 11 is irradiated with a particle beam to emit secondary electrons which are detected by a detector 14 through an electronic spectrometer 13. When spectra of secondary electrons are measured, a gas having a known secondary electron resonance line is encapsulated in the sample chamber 8 and the measurement of energy of secondary electrons emitted from the sample 11 is corrected based on the measurement of energy of the secondary electron resonance line of the gas.