the present invention provides an electron beam measurement technique for measuring the shapes or sizes of portions of patterns on a sample , or detecting a defect or the like . an electron beam measurement apparatus has a unit for irradiating the patterns delineated on a substrate by a multi - exposure method , and classifying the patterns in an acquired image into multiple groups according to an exposure history record . the exposure history record is obtained based on brightness of the patterns and a difference between white bands of the patterns .