An electron microscope according to the present invention includes: a backscattered electron detector provided with a backscattered electron detecting element (9); a low-vacuum secondary electron detector provided with a bias electrode (11) and a specimen stage (12); and a signal switch (14) that switches signals detected by the detectors. Optimal observation conditions are stored in an observation condition memory (20) for each of the detectors. A CPU (19) calls observation conditions stored in the observation condition memory (20) on the basis of the switching of the detectors, and sets conditions of the electron microscope to the called observation conditions. An image processing device (22) converts a plurality of the detected signals obtained on the basis of the switching of the detectors into two-dimensional image signals and evaluates the qualities of images of the two-dimensional image signals. In an image quality prioritized mode, the CPU (19) selects a detector causing an evaluated value to be highest on the basis of the results of the evaluation performed by the image processing device (22) and causes an image to be displayed. In the electron microscope that includes the plurality of detectors, a detector can easily be selected, and the optimal observation conditions for the detectors can easily be set.