A specimen is scanned with an electron beam so as to generate a signal characteristic of the specimen to thereby produce an image thereof on the basis of the generated signal. A memory is provided for storing operating conditions of a scanning electron microscope which are associated with identification information for specifying the specimen. The identification information is designated so that thereby at least one operating condition corresponding to the designated identification information is read out from the memory, and the read out operating condition is automatically set so that the scanning electron microscope is operated under the set operating condition.