[en] Thermal and epithermal neutron activation analysis followed by high resolution gamma-ray spectrometry, is applied to determine trace elements in the silicate rocks. Epithermal neutron irradiations reduce interfering activities such as ³⁸Cl,⁶⁶Cu,⁵⁶Mn,²⁴Na,⁴⁶Sc, etc. The effect is represented as the advantage factors for various elements. The concentrations of 40 elements with the detection limits are determined under the analytical condition. The precision and accuracy of the method are compared with the results of USGS standard's rock, G-2 and AGV-1 analyses. (Author)