In an operation of an electron microscope, at least a spot size of an electron beam on a specimen, an acceleration voltage, a detector type, a specimen position, and an observation magnification are set as a predetermined image observation condition and an observation image is picked up under the predetermined image observation condition. Different image observation conditions are automatically set based on the observation image. A plurality of observation images are picked up based on the setup image observation conditions. The plurality of picked-up observation images are simultaneously displayed on a second display section. A desired observation image is selected from among the observation images displayed on the second display section. The selected observation image is displayed on a first display section on an enlarged scale.