Protons are entered into a substrate to be analyzed at a proton incident angle larger than 0° and smaller 90°. Excited by the entered protons and emitted from the substrate to be analyzed, the characteristic X-ray is measured by an energy dispersive X-ray detector and the like. Impurity elements present in the substrate to be analyzed are identified based on the measured characteristic X-ray. The in-plane distribution in the substrate can be obtained by scanning the proton beam. The in-depth distribution can be obtained by entering protons at different proton incident angles. The elemental analysis method can be applied to semiconductor device manufacturing processes to analyze metal contamination or quantify a conductivity determining impurity element on an inline basis and with a high degree of accuracy.