In order that a displacement between patterns of different heights, formed on a sample in a plurality of different pattern-forming steps, can be measured at fixed throughput and with high accuracy, correspondence between parameters of lenses and beam deflector of an electron optical system and an angle of incidence of a beam upon the sample is recorded as data, then a correction value for the amount of displacement or edge positions is calculated, and a true amount of displacement is calculated from the correction value and an image under observation.