Abstract: An ion microprobe analyzer capable of high-precision analyses, and which provides a beam made up of both ions and neutral particles includes an ion beam deflecting means made up of an aperture which is movable between a position on the ion beam optical axis and a position deviating from the optical axis. At least one first deflector is provided which deflects the ion beam towards the point to be occupied by the aperture situated at the deviating position while leaving the path of the neutral particles unaffected, and at least two second deflectors are provided which deflect the ion beam back towards the ion beam optical axis, so that in the vertical direction the ion beam which has passed through the aperture situated at the deviating position is returned to the optical axis. In this way either the ions or the neutral particles may be selected in accordance with the position of the aperture.