The present invention provides a compact
electron lens causing little aberration, and a
charged particle beam apparatus such as a
scanning electron microscope that is super compact and offers a
high resolution. An upper magnetic pole and a sample-side magnetic pole are magnetically coupled to the respective poles of a permanent
magnet that is made of a highly strong magnetic material such as a rare-earth
cobalt system or a
neodymium-iron-
boron system, that is axially symmetrical, and that has a hole in the center thereof. An inner gap is created on the side of a center axis. Thus, a
magnetic lens is formed axially. Moreover, a semi-stationary magnetic path that shields an outside
magnetic field and has the
magnetic reluctance thereof regulated is disposed outside. The sample-side magnetic pole and magnetic path defines a region where
magnetic reluctance is the highest outside the permanent
magnet. A space defined by the permanent
magnet, upper magnetic pole, sample-die magnetic pole, and semi-stationary magnetic path is filled with a filling made of a non-magnetic material. Thus, an objective lens is constructed.