a scanning photoelectron microscope comprises a stage on which a sample is placed in a state in which gas around the sample is present , a light source emitting light of a wavelength capable of causing photoelectrons to be emitted from the sample , an optical system for condensing the light from the light source on the sample , scanning means for scanning the sample and the light relative to each other , and detecting means capable of applying positive potential to the sample , and detecting the photoelectrons created from the sample by the condensing , through the gas .