There is provided an energy filter capable of being simplified in structure and of achieving low aberrations. The energy filter (100) includes a first sector magnet (10) and a second sector magnet (20). The first and second magnets (10, 20) are configured mirror-symmetrically with respect to a symmetry plane (M). There are one focal point of crossover in the X direction and one focal point of crossover in the Y direction. The focal point of crossover in the X direction and the focal point of crossover in the Y direction are at an energy dispersive plane (S2). There are two focal points of image in the X direction and two focal points of image in the Y direction. The focal points of image in the X direction and the focal points of image in the Y direction are at the symmetry plane (M) and at an achromatic plane (A2).