According to one embodiment, a contour extraction method for extracting a contour of a target object from an image obtained using an electron beam includes: extracting the contour of the target object from a backscattered electron image; creating a dictionary for associating a secondary electron image obtained from a portion common to the backscattered electron image with the contour; calculating a likelihood of the contour of the target object in a plurality of positions of a newly obtained secondary electron image by referencing the dictionary regarding the newly obtained secondary electron image; and setting a route along which a total sum of the likelihood is maximized out of the plurality of positions as the contour of the target object.