The secondary electrons, from a sample placed within a lens magnetic field, are detected by a plurality of secondary electron detectors, thereby effectively observing a concave/convex in a sample surface. In a scanning electronic beam apparatus having upper and lower electrodes built in a single-pole magnetic-field type lens to place a sample within a lens magnetic field, a negative voltage is applied to the sample and the lower electrode opposed thereto while a zero or positive voltage is applied to the upper electrode, whereby an electric field for suppressing the helical motion of a secondary electron given off from the sample due to electron-beam irradiation is caused within a region of from the sample to an objective lens magnetic field space closer to an electron source. The secondary electron is detected by a division-type MCP or a plurality of scintillator-type secondary electron detectors arranged sandwiching the optical axis.