1. An electron microscope comprising: a plurality of detectors that are different from each other in type of detection method, the plurality of detectors configured to detect signals generated by irradiation of a specimen with an electron beam; a signal switch for switching the signals detected by the plurality of detectors; a storage for storing observation conditions each including a working distance of the electron microscope for a corresponding one of the plurality of detectors; and a controller for reading one of the observation conditions which include the working distance stored in the storage on the basis of switching of the plurality of detectors and changing a position of a specimen stage included in the electron microscope at least upward or downward so that an actual working distance is set to the working distance read by the controller.