1. A scanning electron microscope comprising: an image acquisition unit which scans an electron beam on a sample under specified imaging conditions at each measurement over the number of times of measurement to acquire an enlarged measurement image at high magnification based on an electron signal emitted from the sample; an image processing unit which acquires a roughness template image showing a micro-minute shape of a pattern in a provided local area and an enlarged measurement area image of the local area subjected to two-dimensional pattern matching, from the enlarged measurement image at high magnification acquired at each measurement over the number of times of measurement by the image acquisition unit; a measurement unit which measures typical dimensions or a shape of the pattern in the enlarged measurement area on the basis of the enlarged measurement area image of the local area, which has been acquired at each measurement over the number of times of measurement by the image processing unit; and a measurement repeatability evaluation unit which presents, as an evaluation value of the measurement repeatability as a tool, a value associated with the change in dimensions or the change in shape for the number of times of measurement, said dimensions or said shape being measured over the number of times of measurement by the measurement unit.