An embodiment of the invention relates to a SEM enabling a surface analysis of a sample at a high throughput. The SEM has an electron gun, an irradiation unit, and a detector. The detector, as a first structure, includes an MCP, an anode, and a dynode. The dynode is set at a potential higher than a potential of an output face of the MCP and the anode is set at a potential higher than that of the dynode. The anode is disposed on the dynode side with respect to an intermediate position between the output face of the MCP and the dynode. The anode has an aperture for letting electrons from the output face of the MCP pass toward the dynode.