The SEM has a dynamic range reference value setting unit for setting dynamic range reference values, a dynamic range adjustment unit for receiving an observation image signal delivered out of a secondary electron detector, adjusting the dynamic range of the observation image signal on the basis of the dynamic range reference values and outputting the thus adjusted observation image signal as an observation image signal after adjustment, a display image generation unit for determining luminous intensity levels of individual pixels of an image to be displayed based on the observation image signal after adjustment to generate a display image, a histogram generation unit for generating a histogram of luminous intensity levels of the display image and extracting, as a luminous intensity peak value, at which the frequency of luminous intensity is maximized, and a display unit for displaying the generated histogram and the extracted luminous intensity peak value.