To improve operability by automatically switching on and off the acceleration of the frame rate.

This is an electron microscope that comprises a frame rate accelerating function in which electron beams are irradiated on the sample by impressing an accelerating voltage on the electron gun based on the prescribed observation condition, and which scans the desired area on the sample surface by detecting the secondary electrons or reflecting electrons by one or more detectors, and by imaging the observed image, can display by the display part, and further, accelerates the speed required for image description of the observed image displayed on the display part. When a prescribed operation is instructed to the image of the observed image, the frame rate accelerating function is implemented, and when there are no operations on the image of the observed image for a certain time or more, the frame rate accelerating function is automatically stopped.