Electron-probe microanalysis (EPMA) of the wavelength-dispersive (WD) type offers some advantage in each quan-titative analysis of various kind of rare-earth elements in minerals with their high concentrations. Close observation on WD spectra of REE in minerals leads to a skillful selection including the favorable conditions: a suitable choice of background mea-surement positions, 25kV (accelerating voltage), LW crystal, the beam size of 20μm, emission current of 1×10^-8A, and the ZAF corrections. This accelerating voltage is indispensable in quantitatively analyzing various kinds of REE in minerals. As tested on thortveitite, the present EPMA has proved to be correct for REE-pyrosilicates.