PURPOSE:To facilitate the removal of the strain of a level image due to the drift of a sample to be measured and a comparison and a contrast with a secondary electronic image by constituting a picture at high speed without executing the reduction treatment of noises and continuously displaying the picture on a display device. CONSTITUTION:Electron beams are swept in a region to be observed on a sample to be measured 2, and a signal from a level in the sample and a transient response containing noises are by a capacity meter 5 measured under the state in which fixed voltage is applied by a DC power supply 6. Obtained transient response is transmitted directly over a level amplitude detector 8 without reducing noises, and a signal output corresponding to level density at some point is acquired. The signal output is inputted to a display device 11 synchronizing with the electron-beam sweeping of a scanning electron microscope 1 through an amplifier 13. Accordingly, a two-dimensional image at the level is obtained at approximately the same speed as the measurement of a secondary electronic image. The reduction of mixed noises is realized by continuously displaying the acquired image and effectively equalizing the image as a system containing human eyes or a photograph or the like.