A scanning electron microscope includes an electron beam source which emits an electron beam, a beam current controller which controls a beam current of the electron beam, an electron beam converger which converges the electron beam on a surface of a sample, an electron beam scanner which scans the electron beam on the surface of the sample, a table which mounts the sample and moves at least in one direction, a detector which detects a secondary electron or a reflected electron emanated from the sample by the scan of the electron beam, an image former which forms an image of the sample based on a detection value of the detector, an image processor which processes the image formed by the image former. The beam current controller controls the beam current of the electron beam by changing transmittance of the electron beam in an irradiation path of the electron beam.