PURPOSE: To make a sufficient photoelectron spectroscopy in a minute region of a sample possible, by providing a means which varies the section of an electron beam, an aperture which changes the size of an X-ray passage hole, and a displacing means which displaces a target relatively.

CONSTITUTION: A thermoelectron flux E from a filament 1 is shaped by an electron shaping lens 5 to give such size to the section of the thermoelectron flux E that the quantity of X rays required for analysis is generated. For the purpose of cutting X rays around X rays, which have the section having a prescribed size, from an X-ray target 2 by an aperture 7, U-shaped plates 7A and 7B are moved properly in X and Y directions by an aperture moving mechanism 8.