In an interference electron microscope, a first electron biprism is disposed between an acceleration tube and an illumination-lens system, a mask is disposed between the acceleration tube and the first electron biprism, and the first electron biprism is arranged in a shadow that the mask forms. Current densities of first and second electron beams on a parabolic surface of an objective lens system where a sample is positioned are controlled by a control system by an optical action of the illumination-lens system, the mask is imaged on the parabolic surface of the objective lens system, and an electro-optical length between the first electron biprism and the parabolic surface of the objective lens where the sample is positioned is controlled without generating Fresnel fringes on a sample surface from the mask and the first electron biprism.