an electron microscope includes an electron gun for generating an electron beam , an accelerator for accelerating the electron beam to apply the electron beam to a sample , a spectroscope for selecting electrons having a specific energy out of the electron beam transmitted through the sample and losing an energy by an interaction with the sample , and a detector for detecting the electrons of the specific energy selected by the spectroscope and giving a transmission signal or a diffraction signal at a depth of the sample corresponding to a lost energy quantity of the electrons .