In the present invention, an overlay misalignment is quickly measured. An image generation unit generates an image on the basis of signals from a detector. A matching processing unit identifies, by means of matching processing with a template image, the position of an overlay measurement pattern in the image generated by the image generation unit. A line profile generation unit generates, by scanning the overlay pattern, a first line profile pertaining to a secondary electron signal and a second line profile pertaining to a backscattered electron signal. An overlay misalignment measurement unit identifies the position of a first pattern in the overlay measurement pattern from the first line profile, identifies the position of a second pattern in the overlay measurement pattern from the second line profile, and measures an overlay misalignment in a sample on the basis of the position of the first pattern and the position of the second pattern.