There is provided a method of adjusting a transmission electron microscope to facilitate an adjustment for bringing a focal plane of an electron beam exiting a two-stage filter type monochromator into coincidence with an achromatic plane. The method starts with obtaining a transmission electron microscope image including interference fringes of the electron beam that are generated by an aperture located behind the monochromator. The focal plane of the beam exiting the monochromator is brought into coincidence with the achromatic plane by adjusting the intensity of an electrostatic lens, the intensities of the electric and magnetic fields produced by at least one of two energy filters, or astigmatism generated in the monochromator based on an intensity distribution of the interference fringes in the obtained transmission electron microscope image.