PROBLEM TO BE SOLVED: To provide a scanning electronic microscope capable of observing a reflection electron detection image having a high brightness at the same sample position as 2 electron detection image having a high resolving power. SOLUTION: The scanning electron microscope is provided with an objective lens having an inner magnetic pole and an outer magnetic pole and forming a lens magnetic field below a lower end surface of the magnetic pole, a scanning means for scanning an irradiation position of an electron beam on a sample; by focusing the electron beam by the objective lens to irradiate thereto and a reflection detection for detecting a reflection electron obtained by an irradiation of the electron beam to the sample. Openings are provided on the inner magnetic pole and the outer magnetic pole of the objective lens and the reflection electron detector can be inserted/retracted to an electron beam passage part in the objective lens through the opening.
