The present invention provides a scanning charged particle beam device including a sample chamber (8) and a detector. The detector has: a function of detecting light at least ranging from the vacuum ultraviolet region to the visible light region, of light (17) having image information which is obtained by a light emission phenomenon of gas scintillation when the sample chamber is controlled to a low vacuum (1 Pa to 3,000 Pa); and a function of detecting ion currents (11, 13) having image information which are obtained by cascade amplification of electrons and gas molecules. Accordingly, it becomes possible to realize a device which can deal with observation of various samples. Further, an optimal configuration of the detection unit is devised, to thereby make it possible to add value to an obtained image and provide users in wide-ranging fields with the observation image. In addition, the detector is made usable in combination with a detector for high vacuum, to thereby make it possible to provide wide-ranging users with the image, irrespective of the vacuum mode.