1. A scanning electron microscope which scans an electron beam, irradiates the electron beam onto a sample, and detects a signal emitted from the sample so as to form an image, the microscope comprising: an image recording unit that records a plurality of frame images each of which is acquired by scanning an observation field of the sample once; a correction analyzing handling unit that obtains a drift rate between the frame images and a drift rate between the field images included in each of the frame images; and a data handling unit that corrects the drift of the field images based on the drift rate between the field images, and superimposes the field images.