An electron microscope includes an electron source, an extraction electrode that extracts an electron beam emitted from the electron source, a monochromator having an energy filter that disperses the electron beam emitted from the electron source based on an energy thereof and an energy selection slit that selects the energy of the electron beam, an incident-side electrode provided between the extraction electrode and the monochromator, and an incident-side electrode controller that controls the incident-side electrode based on a change in a voltage applied to the extraction electrode.