The purpose of the invention is to provide an improved electron beam apparatus with improvements in throughput, accuracy, etc. One of the characterizing features of the electron beam apparatus of the present invention is that it has a plurality of optical systems, each of which comprises a primary electron optical system for scanning and irradiating a sample with a plurality of primary electron beams; a detector device for detecting a plurality of secondary beams emitted by irradiating the sample with the primary electron beams; and a secondary electron optical system for guiding the secondary electron beams from the sample to the detector device; all configured so that the plurality of optical systems scan different regions of the sample with their primary electron beams, and detect the respective secondary electron beams emitted from each of the respective regions. This is what makes higher throughput possible. To provide high accuracy, the apparatus is configured such that the axes of its optical systems can be aligned, and aberrations corrected, by a variety of methods.